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Orion 5.0 moved to [https://github.com/nzakas/eslint/ ESLint] as the validator that ships with Orion. This page captures ongoing issues.
+
Orion 5.0 introduced [https://github.com/nzakas/eslint/ ESLint] as the validator that ships with Orion. This page captures ongoing issues.
  
== Rule parity ==  
+
== Rules ==  
Here's a table showing the equivalent validation rules in JSLint and ESLint. Rules that JSLint does not support are marked as Unsupported.  
+
The following sections describe all of the rules currently available in Orion and ones that we plan to add in the future.
  
{| class="wikitable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
+
'''To view this table in the same order as the Orion Settings page, hover over the ''Setting Message'' column title and press the down arrow to sort.'''
! style="background:#efefef;" | ESLint rule
+
! style="background:#efefef;" | JSLint option
+
! style="background:#efefef;" | JSLint message
+
! style="background:#efefef;" | Details
+
|-
+
  
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428433 block-scoped-var]
+
=== Potential Programming Problems ===
| Always on
+
These rules report about problems with your code that might have undesired or incorrect results. Warnings from these
| '''{variable}' is already defined.''
+
rules should be addressed.
|
+
* Occurs when a function-scoped variable is treated as if it was block scoped.
+
* ESLint calls this error '{variable} used outside of binding context.'
+
|-
+
  
!| brace-style
+
{| class="wikitable sortable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
| Unsupported
+
! width=13% | Rule
|  
+
! width=5% | Default Severity
|  
+
! width=3% | Available Since
 +
! width=24% | Setting Message
 +
! width=24%| Problem Message
 +
! width=24% | Details
 +
! width=3% | Quick Fix?
 +
! width=3% | Fix All?
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455253 no-comma-dangle]
!| camelcase
+
| Ignore
| Unsupported
+
|style="text-align:center;"| 8.0
|  
+
|Trailing commas in object expressions
|  
+
| ''Trailing commas in object expressions are discouraged.''
 +
| Flags trailing commas in object expressions.
 +
|style="text-align:center;" | ✔
 +
|style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455250 no-cond-assign]
!| complexity
+
| Error
| Unsupported
+
|style="text-align:center;"| 8.0
|
+
|Assignments in conditional expressions
|  
+
| ''Expected a conditional expression and instead saw an assignment.''
 +
| Flags assignment in an <code>if/while/do..while/for</code> condition.
 +
| style="text-align:center;" | ✔
 +
|style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455371 no-console]
!| consistent-this
+
| Ignore
| Unsupported
+
|style="text-align:center;"| 8.0
|
+
|Discouraged console use in browser code
 +
| ''Discouraged use of console in browser-based code.''
 +
| Flags the use of console in browser-based code
 
|  
 
|  
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455680 no-constant-condition]
!| curly
+
| Error
| Always on
+
|style="text-align:center;"| 8.0
 +
|Constant as conditional expression
 +
| ''...'' is constant.
 +
| Flags the use of a constant as a conditional expression
 +
|
 
|
 
|
* ''Statement body should be inside '{ }' braces.'' (Orion)
 
* ''Expected '{'.'' (Regular JSLint)
 
|
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455680 no-const-assign]
!| dot-notation
+
| Error
| '''sub'''
+
|style="text-align:center;"| 13.0
| ''{a} is better written in dot notation.''
+
| Disallow modifying variables that are declared using const
|  
+
| ''Discouraged use of constant as a conditional expression.''
|-
+
| Flags the assignment to a constant variable
 
+
!| eqeqeq
+
| '''eqeqeq''' or '''eqeq'''
+
 
|
 
|
* ''Expected '===' and saw '=='.''
 
* ''Expected '!==' and saw '!='.''
 
 
|
 
|
* Newer versions of JSLint call this option '''eqeqeq'''.
 
* Orion's version calls it '''eqeq''', and inverts the flag's value.
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-control-regex]
!| guard-for-in
+
| Error
| '''forin'''
+
|style="text-align:center;"| 11.0
| ''The body of a <code>for in</code> should be wrapped in an <code>if</code> statement to filter unwanted properties from the prototype.''
+
|Disallow control characters in regular expressions
 +
| ''Unexpected control character in regular expression''
 +
| Control characters are special, invisible characters in the ASCII range 0-31. These characters are rarely used in JavaScript strings so a regular expression containing these characters is most likely a mistake.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429690 no-debugger]
!| max-depth
+
| Warning
| Unsupported
+
|style="text-align:center;"| 6.0
|  
+
|Discouraged 'debugger' statement use
| Enforces max depth of nested blocks within a function.
+
| ''debugger' statement use is discouraged.''
 +
| Warns when the <code>debugger</code> keyword is used
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485767 ✔]
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485767 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428430 no-dupe-keys]
!| max-len
+
| Error
| '''maxlen'''
+
|style="text-align:center;"| 6.0
| ''Line too long.''
+
|Duplicate object keys
| Enforces a maximum line length.
+
| ''Duplicate object key '{key}'.''
 +
| Flags object literals that contain the same key more than once.
 +
| style="text-align:center;" |[https://bugs.eclipse.org/bugs/show_bug.cgi?id=485953 ✔]
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-duplicate-case]
!| max-params
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
 +
|Duplicate case
 +
| ''Duplicate case label.''
 +
| A switch statements with duplicate case labels is normally an indication of a programmer error.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=439366 no-empty-block]
 +
| Ignore
 +
|style="text-align:center;"| 7.0
 +
|Undocumented empty block
 +
| ''Empty block should be removed or commented.''
 +
| Flags an empty block like <code>if (something) { }</code>.
 +
| style="text-align:center;" | ✔
 
|
 
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-empty-character-class]
!| max-statements
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|Disallow empty character classes
 +
| ''Empty class.''
 +
| Empty character classes in regular expressions do not match anything and can result in code that may not work as intended.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-extra-boolean-cast]
!| new-cap
+
| Error
| '''newcap'''
+
|style="text-align:center;"| 11.0
| ''A constructor name should start with an uppercase letter.''
+
|Discourage redundant double negation
 +
| Redundant double negation in ...
 +
| In contexts such as an if statement's test where the result of the expression will already be coerced to a Boolean, casting to a Boolean via double negation (!!) is unnecessary.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-extra-parens]
!| new-parens
+
| Warning
| Always on
+
|style="text-align:center;"| 11.0
| ''Missing '()' invoking a constructor.''
+
| Discourage redundant parentheses
| Flags <code>new Whatever</code>
+
| ''Gratuitous parentheses around expression.''
 +
| This rule restricts the use of parentheses to only where they are necessary. It may be restricted to report only function expressions.
 +
|style="text-align:center;" | ✔
 +
|style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428040 no-extra-semi]
!| no-alert
+
| Warning
| '''devel'''
+
|style="text-align:center;"| 5.0
| '''{alert, confirm, prompt}' is not defined.''
+
|Unnecessary semicolons
|  
+
| ''Unnecessary semicolon.''
 +
| Warns when a semicolon is found where it is not needed
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429815 no-fallthrough]
!| no-bitwise
+
| Error
| '''bitwise'''
+
|style="text-align:center;" | 6.0
| ''Unexpected use of '{operator}'.''
+
|Switch case fall-through
| JSLint disallows bitwise ops by default.
+
| ''Switch case may be entered by falling through previous case. If intended, add a new comment //$FALL-THROUGH$ on the line above''
 +
| Flags a fallthrough case within a <code>switch</code> statement, unless it is explicitly commented.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-invalid-regexp]
!| no-caller
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|Invalid regular expressions
| Flags references to <code>arguments.callee</code> and <code>arguments.caller</code>.
+
| ''Invalid flags supplied to RegExp constructor '{${0}}'.'' or the error message from calling the constructor with the regex
 +
| This rule validates string arguments passed to the RegExp constructor.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=482616 no-irregular-whitespace]
!| no-catch-shadow
+
| Ignore
| Always on
+
|style="text-align:center;"| 11.0
| '''{a}' is already defined.''
+
| Report irregular whitespace
|
+
| '''Irregular whitespace not allowed''
* Flags a <code>catch</code> clause's variable that shadows a variable declared in an outer scope. (In IE8 this [weblog.bocoup.com/the-catch-with-try-catch/ causes the outer variable to be overwritten]).
+
| This rule validates all whitespaces
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-negated-in-lhs]
!| no-comma-dangle
+
| Error
| Always on
+
|style="text-align:center;"| 11.0
| ''Unexpected comma.''
+
|Disallow negated left operand of in operator
| Flags trailing commas in object literals.
+
| ''The 'in' expression's left operand is negated.''
 +
| Disallow negated left operand of in operator
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-obj-calls]
!| no-cond-assign
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|Disallow global object as function calls
| Flags assignment in an <code>if/while/do..while/for</code> condition.
+
| '' '{${0}}' is not a function.''
 +
| ECMAScript provides several global objects that are intended to be used as-is. Some of these objects look as if they could be constructors due their capitalization (such as Math and JSON) but will throw an error if you try to execute them as functions.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455391 no-regex-spaces]
!| no-console
+
| Error
| '''devel'''
+
|style="text-align:center;"| 8.0
|  
+
|Multiple spaces in regular expressions
|  
+
| ''Avoid using multiple spaces in regular expressions. Use ' {${0}}' instead.''
 +
| Flags regular expressions that have two or more subsequent spaces.
 +
| style="text-align:center;" |
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455354 no-reserved-keys]
!| no-control-regex
+
| Ignore
| Unsupported
+
|style="text-align:center;"| 8.0
|  
+
|Reserved words used as property keys
| Flags control characters (U+0000–U+001F and U+007F) within the source argument to the RegExp constructor.
+
| ''Reserved words should not be used as property keys.''
 +
| Checks to see if a JavaScript reserved word is being used as a property key
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485980 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=426723 no-sparse-arrays]
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429690 no-debugger]
+
| Warning
| '''debug'''
+
|style="text-align:center;"| 8.0
| ''All 'debugger' statements should be removed.''
+
|Sparse array declarations
|  
+
| ''Sparse array declarations should be avoided.''
 +
| Flags sparse arrays with null elements like <code>var arr = [1, ,2]</code>
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=436986 no-unreachable]
!| no-delete-var
+
| Warning
| Always on
+
|style="text-align:center;"| 6.0
| ''Expected '.' and instead saw ';'.''
+
|Unreachable code
| Flags an attempt to <code>delete</code> a local variable.
+
| ''Unreachable code.''
 +
| Flags statements that occur after a <code>return</code>, <code>throw</code>, etc.
 +
| style="text-align:center;" | ✔
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=425200 type-checked-consistent-return]
!| no-div-regex
+
| Ignore
| Always on
+
|style="text-align:center;"| 11.0
| ''A regular expression literal can be confused with '/='.''
+
|Discouraged inconsistent returns
| Flags a regex literal starting with <code>/=</code>
+
| ''Inconsistent return types: (type1) (type2)''
 +
| Warns when a function returns two values with different types.
 +
| style="text-align:center;" |
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429711 use-isnan]
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428429 no-dupe-keys]
+
| Error
| Always on
+
|style="text-align:center;"| 6.0
| ''Duplicate key '{a}'.''
+
|NaN not compared with isNaN()
| Flags object literals that contain the same key more than once.
+
| ''Use the isNaN function to compare with NaN.''
 +
| Warns when a comparison is done against NaN without using the <code>isNaN</code> function
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=470189 ✔]
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485977 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=447189 valid-typeof]
!| no-else-return
+
| Error
| Unsupported
+
|style="text-align:center;"| 7.0
 +
|Invalid 'typeof' comparison
 +
| ''Invalid typeof comparison.''
 +
| Warns when a typeof comparison uses an invalid type.
 
|  
 
|  
| Flags an <code>else</code> appearing after an <code>if</code> that contains a <code>return</code>.
+
|
 
|-
 
|-
 +
|}
  
!| no-empty-class
+
=== Best Practices ===
| Always on
+
These rules are not necessarily problem with your code, but are warnings that you might be doing something
| ''Empty class.''
+
you probably should not be.
| Flags an empty character class <code>[]</code> within a regular expression.
+
|-
+
  
!| no-empty-label
+
{| class="wikitable sortable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
| Always on
+
! width=13% | Rule
| ''Label '{a}' on statement.''
+
! width=5% | Default Severity
| Flags a labeled statement that is not a <code>switch</code>, <code>for</code>, or <code>while</code>.
+
! width=3% | Available Since
 +
! width=24% | Setting Message
 +
! width=24%| Problem Message
 +
! width=24% | Details
 +
! width=3% | Quick Fix?
 +
! width=3% | Fix All?
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 accessor-pairs]
!| no-empty
+
| Warning
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|Getter and setter accessors not in pairs
| Flags an empty block like <code>if (something) { }</code>.
+
| ''Getter is not present'' or ''Setter is not present''
 +
| It's a common mistake in JavaScript to create an object with just a setter for a property but never have a corresponding getter defined for it. Without a getter, you cannot read the property, so it ends up not being used.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=490332 check-tern-plugin]
!| no-eq-null
+
| Warning
| Always on
+
|style="text-align:center;" | 12.0
| ''Use '===' to compare with 'null'.''
+
|Missing .tern-project plugins entry for environment directive
| JSLint produces a similar warning when comparing against <code>undefined</code>.
+
| ''To work in the 'foo' environment, the 'bar' plugin must be running.''
 +
| Warn when the an eslint-env directive specifies a library Orion provides tooling support for, but the library plugin has been disabled in the .tern-project file.
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=490332 ✔]
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=487279 curly]
!| no-eval
+
| Ignore
| '''evil'''
+
|style="text-align:center;" | 6.0
| ''eval is evil.''
+
|Statements not enclosed in braces
 +
| ''Statements should be enclosed in braces.''
 +
| Warns when statements should be enclosed in braces, for example <code>if(something) foo();</code>
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=454641 ✔]
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=414779 eqeqeq]
!| no-ex-assign
+
| Warning
| Always on
+
|style="text-align:center;" | 5.0
| ''Do not assign to the exception parameter.''
+
|Discouraged '==' use
 +
|
 +
* ''Expected '===' and saw '=='.''
 +
* ''Expected '!==' and saw '!='.''
 +
| Warns when <code>==</code> or <code>!=</code> is used
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=493019 missing-requirejs]
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428040 no-extra-semi]
+
| Warning
| Always on
+
|style="text-align:center;" | 12.0
| ''Unnecessary semicolon.''
+
|'requirejs' plugin missing in AMD environment
 +
| To use AMD, the 'requirejs' plug-in needs to be running.
 +
| Flags references to function calls from AMD when the Tern 'requirejs' plugin is not running
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=493019 ✔]
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=460976 no-caller]
!| no-fallthrough
+
| Error
| Unsupported
+
|style="text-align:center;" | 9.0
|  
+
|Discouraged 'arguments.caller' or 'arguments.callee' use
| Flags a fallthrough case within a <code>switch</code> statement, unless it is explicitly commented.
+
| ''arguments.{callee, caller} is deprecated.''
 +
| Flags references to <code>arguments.callee</code> and <code>arguments.caller</code>.
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=459934 Future]
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-else-return]
!| no-floating-decimal
+
| Warning
| Always on
+
|style="text-align:center;"| 11.0
| ''A {leading, trailing} decimal point can be confused with a dot: '{n}'.''
+
|Unnecessary else after return
| Flags numeric literals that have a leading or trailing decimal point.
+
| ''Unexpected 'else' after 'return'.''
 +
| If an if block contains a return statement, the else block becomes unnecessary. Its contents can be placed outside of the block.
 +
| style="text-align:center;" | ✔
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-empty-label]
!| no-func-assign
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|No empty labels
| Flags assignment to a variable that's already bound to a <code>FunctionExpression</code>.
+
| ''Unexpected label "{${0}}"''
 +
| Labeled statements are only used in conjunction with labeled break and continue statements. ECMAScript has no goto statement.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=467903 no-eq-null]
!| no-global-strict
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
|  
+
|Disallow null comparisons
| Flags <code>"use strict"</code> applied to the entire Program.
+
| ''Use ‘===’ to compare with ‘null’.'' or ''Use ‘!==’ to compare with ‘null’.''
 +
| Comparing to null without a type-checking operator (== or !=), can have unintended results as the comparison will evaluate to true when comparing to not just a null, but also an undefined value.
 +
|style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485171 ✔]
 +
|style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=485171 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486766 no-extend-native]
!| no-implied-eval
+
| Error
| Always on
+
|style="text-align:center;"| 13.0
| ''Implied eval is evil. Pass a function instead of a string.''
+
| Disallow extending of native objects
| Flags calls to the string-argument form of <code>setTimeout</code> and <code>setInterval</code>, which implicitly perform <code>eval</code>.
+
| '..... prototype is read only, properties should not be added.'
 +
| Disallows directly modifying the prototype of builtin objects.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486765 no-extra-bind]
!| no-iterator
+
| Warning
| Always on
+
|style="text-align:center;" | 13.0
| ''Reserved name '__iterator__'.''
+
|Unnecessary 'bind()' use
| Flags use of __iterator__ as an identifier name or property key.
+
| ''The function binding is unnecessary.''
 +
| Warns about unnecessary use of bind()
 +
|style="text-align:center;" | ✔
 +
|style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429702 no-eval]
!| no-label-var
+
| Ignore
| Always on
+
|style="text-align:center;" | 6.0
| '''{label}' is already defined.''
+
|Discouraged 'eval()' use
| Flags labels that collide with an identifier.
+
| '''eval' function calls are discouraged.''
 +
| Warns when the <code>eval()</code> function is used
 +
|
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486764 no-implicit-coercion]
!| no-loop-func
+
| Warning
| Always on
+
|style="text-align:center;" | 13.0
| ''Don't make functions within a loop.''
+
|Disallow the type conversion with shorter notations.
 +
| ''use `Boolean(..)` instead.'', ''use `...indexOf(".") !== -1` instead.'', ''use `Number(..)` instead.'', ''use `String(foo)` instead.''
 +
| This rule is aimed to flag shorter notations for the type conversion, then suggest a more self-explanatory notation.
 +
|
 
|
 
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461929 no-implied-eval]
!| no-mixed-requires
+
| Ignore
 +
|style="text-align:center;" | 6.0
 +
|Discouraged implied 'eval()' use
 +
| ''Implicit 'eval' function calls are discouraged.''
 +
| Flags calls to the string-argument form of <code>setTimeout</code> and <code>setInterval</code>, which implicitly perform <code>eval</code>. This rule logic was merged to be part of the <b>no-eval</b> rule.
 
|  
 
|  
 +
|
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486763 no-invalid-this]
 +
| Warning
 +
|style="text-align:center;" | 13.0
 +
|Discouraged 'this' use outside of classes or class-like objects
 +
| ''Unexpected 'this'''
 +
| This rule aims to flag usage of 'this' keywords outside of classes or class-like objects
 
|  
 
|  
| Flags Node.js <code>require()</code>s that mix different types of requires (core, module, file, computed).
+
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455643 no-iterator]
!| no-multi-str
+
| Error
|  
+
|style="text-align:center;" | 8.0
 +
|Discouraged __iterator__ property use
 +
| ''Discouraged __iterator__ property use.''
 +
| Flags use of <code>__iterator__</code> as an identifier name or property key.
 
|  
 
|  
| Flags use of ES5 multiline string literals.
+
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486761 no-lone-blocks]
!| no-native-reassign
+
| Ignore
| Always on
+
|style="text-align:center;" | 13.0
 +
|Discouraged lone block use
 +
| ''Block is redundant.'' or ''Nested block is redundant.''
 +
| Flags use of unnecessary and potentially confusing blocks at the top level of a script or within other blocks.
 +
| style="text-align:center;" |
 
|
 
|
* ''Read only.''
 
* ''Bad assignment.'' (if assigning to <code>undefined</code>)
 
| Flags an attempt to reassign a native object like <code>Math</code>, Array, <code>undefined</code>, etc.
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486760 no-native-reassign]
!| no-negated-in-lhs
+
| Error
| Unsupported
+
|style="text-align:center;" | 13.0
 +
| Disallow reassignment of native objects
 +
| ''... is a read-only native object.''
 +
| This rule flags modifications to read-only global variables
 
|  
 
|  
 
|
 
|
* Flags a unary <code>!</code> operator applied to the LHS of an in statement, which negates the LHS, not the <code>in</code>.
 
* Eg. <code>(!"key" in {key: 1})</code> (which always evaluates to false), will be flagged.
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429817 no-new-array]
!| no-new-array
+
| Warning
| Always on
+
|style="text-align:center;" | 6.0
 +
|Discouraged 'new Array()'
 
| ''Use the array literal notation [].''
 
| ''Use the array literal notation [].''
| Flags <code>new Array()</code>.
+
| Flags <code>new Array()</code>. ESLint calls this rule <code>no-array-constructor</code>
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429817 no-new-func]
!| no-new-func
+
| Warning
| Always on
+
|style="text-align:center;" | 6.0
 +
|Discouraged 'new Function()'
 
| ''The Function constructor is eval.''
 
| ''The Function constructor is eval.''
|  
+
| Flags <code>new Function()</code>.
 +
| style="text-align:center;" |
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429817 no-new-object]
!| no-new-object
+
| Warning
| Always on
+
|style="text-align:center;" | 6.0
 +
|Discouraged 'new Object()'
 
| ''Use the object literal notation {}.''
 
| ''Use the object literal notation {}.''
 
| Flags <code>new Object()</code>.
 
| Flags <code>new Object()</code>.
 +
| style="text-align:center;" |
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429817 no-new-wrappers]
!| no-new-wrappers
+
| Warning
|  
+
|style="text-align:center;" | 6.0
 +
|Discouraged wrapper objects
 
| ''Do not use {String, Number, Boolean, Math, JSON} as a constructor.''
 
| ''Do not use {String, Number, Boolean, Math, JSON} as a constructor.''
 
| Flags <code>new</code> applied to any of those.
 
| Flags <code>new</code> applied to any of those.
 +
| style="text-align:center;" |[https://bugs.eclipse.org/bugs/show_bug.cgi?id=485877 ✔]
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486758 no-param-reassign]
!| no-new
+
| Ignore
| Always on
+
|style="text-align:center;" | 13.0
| ''Do not use 'new' for side effects.''
+
| Disallow Reassignment of Function Parameters
| Flags uses of <code>new</code> operator in an expression that is not assigned to anything.
+
|-
+
 
+
!| no-obj-calls
+
| Partial support
+
| ''Math is not a function..''
+
 
|
 
|
* Flags attempts to call object properties of the global object (<code>Math</code>, <code>JSON</code>) as a function, like <code>Math()</code>.
+
* ''Assignment to function parameter 'bar'.''
* JSLint warns only on <code>Math()</code>.
+
* ''Assignment to property of function parameter 'bar'.''
|-
+
| Report parameter reassignment inside functions. Can also report reassignment of parameter's properties.
 
+
!| no-octal-escape
+
| Always on
+
| ''Bad escapement.''
+
| Flags octal escapes in strings, for example <code>var x = "Copyright \251";</code>
+
|-
+
 
+
!| no-octal
+
| Always on
+
| ''Don't use extra leading zeros '{n}'.''
+
| Flags number literals that begin with leading 0s, which indicate a (probably accidental) octal literal.
+
|-
+
 
+
!| no-plusplus
+
| '''plusplus'''
+
 
|  
 
|  
* ''Unexpected use of '++'''
+
|
* ''Unexpected use of '--'''
+
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461848 no-proto]
!| no-proto
+
| Error
| Always on
+
|style="text-align:center;" | 9.0
 +
|Discouraged __proto__ property use
 +
|
 +
* ''Reserved name '__proto__' should not be assigned.''
 +
* ''Reserved name '__proto__' should not be used as a key.''
 +
| Flags use of the property <code>__proto__</code> as object keys or in assignments
 +
|  
 
|
 
|
* ''Reserved name '__proto__'.'' (if used as an identifier)
 
* ''Stupid key '{a}'.'' (if used as a key)
 
| Treated as a fatal parse error in JSLint.
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=414779 no-redeclare]
!| no-redeclare
+
| Warning
| Always on
+
|style="text-align:center;" | 5.0
 +
|Variable re-declarations
 
| '''{a}' is already defined.''
 
| '''{a}' is already defined.''
 
| Usually results from having two <code>for</code> loops in the same function that share a loop variable declaration like <code>var i=...</code>.
 
| Usually results from having two <code>for</code> loops in the same function that share a loop variable declaration like <code>var i=...</code>.
|-
+
| style="text-align:center;" |
 
+
!| no-return-assign
+
| Unsupported
+
|  
+
 
|
 
|
* Prevents assignment in a <code>return</code> statement.
 
* Unsupported by JSLint, although JSLint does require parens around a return-assignment, eg: <code>return (x = 2);</code>
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=463490 no-self-assign]
!| no-script-url
+
| Error
| Always on
+
|style="text-align:center;" | 11.0
| ''Script URL.''
+
|Disallow self assignment
|  
+
| '''{a}' is assigned to itself.''
* Flags string literals beginning with <code>javascript:</code>. (Script URLs are a form of <code>eval</code>.)
+
| Warns when a variable is being assigned to itself
* Fatal parse error in JSLint.
+
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486124 ✔]
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486124 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461850 no-self-compare]
!| no-self-compare
+
| Error
| Unsupported
+
|style="text-align:center;"| 11.0
 +
|Disallow self compare
 +
| ''Comparing to itself is potentially pointless.''
 +
| Comparing a variable against itself is usually an error, either an typo or refactoring error. It is confusing to the reader and may potentially introduce a runtime error.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=438319 no-shadow]
 +
| Warning
 +
|style="text-align:center;" | 8.0
 +
|Variable shadowing
 +
| '''{a}' is already declared in the upper scope.''
 +
| Flags variables that have the same name as a variable declared in an upper scope.
 +
| style="text-align:center;" | ✔
 
|
 
|
| Flags comparisons where the left- and right-hand sides are the same.
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461321 no-shadow-global]
!!| no-shadow
+
| Warning
| Unsupported
+
|style="text-align:center;" | 9.0
|  
+
|Global shadowing
| Flags variables that have the same name as a variable declared in an outer scope.
+
| '''{a}' shadows a global member.''
|-
+
| Flags variables that have the same name as a variable declared in the global scope or specified environments.
 
+
| style="text-align:center;" |
!| no-spaced-func
+
|
+
|
+
|-
+
 
+
!| no-sync
+
| '''stupid'''
+
| ''Unexpected sync method: '{a}'.''
+
 
|
 
|
* Flags Node.js's synchronous I/O methods.
 
* The '''stupid''' option is supported only in newer versions of JSLint (not Orion's).
 
 
|-
 
|-
 
+
!style="text-align:left;"| [http://git.eclipse.org/c/orion/org.eclipse.orion.client.git/commit/?id=6e517847ef0742b090130748fb9a0329d33e16bf no-throw-literal]
!| no-ternary
+
| Warning
| Unsupported
+
|style="text-align:center;" | 9.0
|  
+
|Literal used in 'throw'
| Flags any use of the ternary operator <code>cond ? thenExpr : elseExpr</code>
+
| ''Throw an Error instead.''
 +
| Flags code that throws a literal, eg. <code>throw "a problem occurred";</code>
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=414779 no-undef]
!| no-undef-init
+
| Error
| Always on
+
|style="text-align:center;" | 5.0
| ''It is not necessary to initialize '{variable}' to 'undefined'.''
+
|Undeclared global reference
|  
+
|-
+
 
+
!| no-undef
+
| '''undef'''
+
 
| '''{variable}' is not defined.''
 
| '''{variable}' is not defined.''
 
|
 
|
* Flags references to a global variable that is not listed in a /*global*/ or /*globals*/ block.
+
* Flags references to a global variable that is not listed in a <tt>/*global*/</tt> or <tt>/*globals*/</tt> block.
* Predefined environments (eg. '''node''', '''browser''') can be set in the /*jslint */ block.
+
* Predefined environments (eg. '''node''', '''browser''', '''amd''') can be set in a <tt>/*eslint-env*/</tt> block.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461852 no-undef-expression]
!| no-underscore-dangle
+
| Warning
| '''nomen'''
+
|style="text-align:center;" | 12.0
| ''Dangling '_'''
+
|Undeclared function reference
 +
| '''{member}' is undefined for '{object}' in {file}.''
 +
| Flags references to a function that is not known to be a property of an object. Will only warn if the object has known properties.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461852 no-undef-init]
!| no-unreachable
+
| Warning
| Always on
+
|style="text-align:center;" | 9.0
| ''Unreachable '{statement}' after '{control flow statement}'.''
+
| Undeclared function reference
| Flags statements that occur after a <code>return</code>, <code>throw</code>, etc.
+
| ''Avoid explicitly initializing variables to 'undefined'.''
 +
| Avoid initializing variables to undefined.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486757 no-unused-expressions]
!| no-unused-expressions
+
| Ignore
| Always on
+
|style="text-align:center;" | 13.0
 +
| Unused expressions
 
| ''Expected an assignment or function call and instead saw an expression.''
 
| ''Expected an assignment or function call and instead saw an expression.''
| Flags expressions that appear in a statement context and don't cause side effects.
+
| Flags expressions that have no effect on the running code
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427310 no-unused-params]
!| no-unused-vars
+
| Warning
| Always on
+
|style="text-align:center;" | 6.0
| ''Function declares unused variable '{a}'.'' (Orion)
+
|Unused parameters
| Newer JSlint versions have an '''unparam''' option which works similarly.
+
| ''Parameter '{param}' is not used.''
 +
| Flags parameters in function declarations / expressions if they are not being used
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=414779 no-unused-vars]
 +
| Warning
 +
|style="text-align:center;" | 5.0
 +
| Unused variables
 +
|
 +
*'''{a}' is unread.''
 +
*'''{a}' is read-only.''
 +
*'''{a}' is unused.''
 +
* ''Function '{a}' is unused''
 +
| Warns when a variable is created and not used (read) or a variable that is read-only is assigned to.
 +
Warns when a function is not used.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=414779 no-use-before-define]
!| no-use-before-define
+
| Warning
| Always on
+
|style="text-align:center;" | 5.0
 +
|Member used before definition
 
| '''{a}' was used before it was defined.''
 
| '''{a}' was used before it was defined.''
 +
| Warns when a variable, function or class is used before it is defined
 +
|
 +
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486755 no-void]
!| no-with
+
| Ignore
| Always on
+
|style="text-align:center;"| 13.0
 +
| Disallow use of the void operator.
 +
| Expected 'undefined' and instead saw 'void'.
 +
| Discourage the usage of the void operator.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461854 no-with]
 +
| Warning
 +
|style="text-align:center;" | 9.0
 +
|Discouraged 'with' statement use
 
| ''Expected an identifier and instead saw 'with'.''
 
| ''Expected an identifier and instead saw 'with'.''
 
| Treated as fatal parse error in JSLint.
 
| Treated as fatal parse error in JSLint.
|-
 
 
!| no-wrap-func
 
| Always on
 
| ''Do not wrap function literals in parens unless they are to be immediately invoked.''
 
| Flags a parenthesized function literal that is not immediately invoked, eg. <code>(function fun(){})</code>
 
|-
 
 
!| one-var
 
| '''onevar'''
 
| ''Too many var statements.''
 
| Allows only 1 <code>var</code> statement per function.
 
|-
 
 
!| quote-props
 
| Unsupported
 
 
|  
 
|  
| Requires object literal keys to be quoted with " or '.
+
|
 
|-
 
|-
 
+
!style="text-align:left;"| [http://git.eclipse.org/c/orion/org.eclipse.orion.client.git/commit/?id=f61bdaf06ac2f40eaca4daed39520cd60c41f5f3 radix]
!| quotes
+
| Warning
| Unsupported
+
|style="text-align:center;" | 8.0
|  
+
|Missing radix parameter to parseInt()
| Flags any use of single or double quote marks, depending on setting.
+
|-
+
 
+
!| radix
+
| Always on
+
 
| ''Missing radix parameter.''
 
| ''Missing radix parameter.''
| Affects parseInt().
+
| Warns when parseInt() called without the 2nd parameter (radix).
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=487695 ✔]
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=487695 ✔]
 
|-
 
|-
 
+
!style="text-align:left;"| unknown-require
!| regex-spaces
+
| Warning
| Always on
+
|style="text-align:center;" | 12.0
| ''Spaces are hard to count. Use {n}.''
+
| Validation of the tern settings
 +
| ''This library could not be found, type information for it will be incomplete.''
 +
| Validation of the tern settings for libraries.
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" |
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486754 yoda]
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427930 semi]
+
| Ignore
| Always on
+
|style="text-align:center;" | 13.0
| ''Missing semicolon.''
+
| Require or disallow Yoda Conditions
 +
|
 +
* ''Expected literal to be on the right side of ...''
 +
* ''Expected literal to be on the left side of ...''
 +
| Enforce consistent style of conditions which compare a variable to a literal value.
 +
|
 
|
 
|
 
|-
 
|-
 +
|}
  
!| strict
+
=== Code Style ===
| '''strict'''
+
These rules are not problems in any way but will warn based on certain accepted styles for coding.
|
+
| Flags any code that lacks the <code>"use strict"</code> pragma.
+
|-
+
  
!| unnecessary-strict
+
{| class="wikitable sortable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
| Unsupported
+
! width=13% | Rule
|  
+
! width=5% | Default Severity
| Flags <code>"use strict"</code> on a function when the entire Program is already in strict mode.
+
! width=3% | Available Since
 +
! width=24% | Setting Message
 +
! width=24%| Problem Message
 +
! width=24% | Details
 +
! width=3% | Quick Fix?
 +
! width=3% | Fix All?
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=424128 missing-doc]
!| use-isnan
+
| Ignore
| Always on
+
|style="text-align:center;" | 5.0
| ''Use the isNaN function to compare with NaN.''
+
|Missing JSDoc
 +
| ''Missing documentation for function '{name}'.''
 +
| Flags missing documentation nodes on function declarations and function expressions when they appear as object properties
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486125 ✔]
 +
| style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428429 missing-nls]
 +
| Ignore
 +
|style="text-align:center;" | 9.0
 +
|Non-externalized string literals (missing $NON-NLS$ tag)
 +
| ''Non-externalized string literal '{a}'.''
 +
| Flags String literals that are not properly NLS'd
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486126 ✔]
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429801 new-parens]
 +
| Error
 +
|style="text-align:center;" | 6.0
 +
|Missing parentheses in constructor call
 +
| ''Missing parentheses invoking constructor.''
 +
| Flags <code>new Whatever</code>
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486127 ✔]
 
|
 
|
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=482616 no-mixed-spaces-and-tabs]
!| wrap-iife
+
| Ignore
| '''immed'''
+
|style="text-align:center;"| 11.0
 +
|Mixed spaces and tabs
 +
| ''Irregular whitespace not allowed.''
 +
| Invalid or irregular whitespace causes issues with ECMAScript 5 parsers and also makes code harder to debug in a similar nature to mixed tabs and spaces.
 +
|style="text-align:center;" |
 +
|style="text-align:center;" |
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=438095 no-jslint]
 +
| Warning
 +
|style="text-align:center;" | 7.0
 +
|Unsupported environment directive
 +
| ''The 'jslint' directive is unsupported, please use eslint-env.''
 +
| Flags use of the /* jslint */ directive
 +
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=453322 Future]
 
|
 
|
* ''Wrap the entire immediate function invocation in parens.''
 
* ''Move the invocation into the parens that contain the function.''
 
| Flags missing parens on immediately-invoked functions, eg. <code>function(){ console.log('hi'); }();</code>
 
 
|-
 
|-
 
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=500436 no-trailing-spaces]
!| wrap-regex
+
| Ignore
| Always on
+
|style="text-align:center;" | 13.0
| ''Wrap the /regexp/ literal in parens to disambiguate the slash operator.''
+
| Unsupported environment directive
 +
| ''Trailing spaces not allowed.''
 +
| Flags any trailing spaces
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 
|-
 
|-
 
+
!style="text-align:left;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=482619 quotes]
 
+
| Ignore
|}
+
|style="text-align:center;" | 13.0
 
+
| Validate which quotes should be used (either single, double or backtick (es6 only))
== New rules ==
+
| ''Strings must use doublequote.'', ''Strings must use singlequote.'', ''Strings must use backtick.''
Ideas for new linting rules that we should write.
+
| Warns when a quote is not the expected one
 
+
| style="text-align:center;" |
{| class="wikitable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
+
| style="text-align:center;" |
! style="background:#efefef;" | Name
+
! style="background:#efefef;" | Severity
+
! style="background:#efefef;" | Description
+
 
|-
 
|-
!| object-prototype-external
+
!style="text-align:left;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427930 semi]
 
| Warning
 
| Warning
| Flags calls to methods of <code>Object.prototype</code> that rely on the prototype chain. For example this code should be flagged:
+
|style="text-align:center;" | 5.0
<source lang="javascript" line="line">
+
|Missing semicolons
foo.hasOwnProperty("bar")
+
| ''Missing semicolon.''
</source>
+
| Warns when a semicolon should be used but is not
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 +
|-
 +
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=483010 unnecessary-nls]
 +
| Ignore
 +
|style="text-align:center;" | 11.0
 +
|Unnecessary $NON-NLS$ tags
 +
| ''Unnecessary $NON-NLS$ tag.''
 +
| Flags $NON-NLS$ comments that are not needed to exclude a string literal
 +
| style="text-align:center;" | ✔
 +
| style="text-align:center;" | ✔
 +
|-
 +
|}
  
Example (1) is [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/hasOwnProperty?redirectlocale=en-US&redirectslug=JavaScript%2FReference%2FGlobal_Objects%2FObject%2FhasOwnProperty#hasOwnProperty_as_a_property unsafe], as <code>foo</code> may have a property named <code>hasOwnProperty</code>, or have been constructed via <code>Object.create(null)</code>.
+
=== Future Implementations ===
  
As for this:
+
Rules that are being considered for inclusion or were implemented but removed.
  
<source lang="javascript" line="line" start="2">
+
{| class="wikitable sortable" border="1" cellpadding="5" cellspacing="0" style="width: 100%;"
Object.hasOwnProperty.call(foo, "bar")
+
! width=13% | Rule
</source>
+
! width=5% | Default Severity
 
+
! width=3% | Available Since
Example (2) technically relies on the prototype chain as well: the hasOwnProperty method is defined on Object.prototype, not Object. Object inherits the methods of Object.prototype [http://stackoverflow.com/questions/14817826/difference-between-an-object-and-its-prototype/14817913#14817913 through its prototype chain]. However (2) is unlikely to fail, as sane JavaScript programs will not modify the global objects' prototypes. If we choose to flag (2), it should only be for style.
+
! width=24% | Setting Message
 +
! width=24%| Problem Message
 +
! width=24% | Details
 +
! width=3% | Quick Fix?
 +
! width=3% | Fix All?
 
|-
 
|-
!| <del>[https://bugs.eclipse.org/bugs/show_bug.cgi?id=424128 missing-doc]</del>
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428433 block-scoped-var]
| Ignore
+
| Error
| Flags missing documentation nodes on function declarations and function expressions when they appear as object properties
+
|style="text-align:center;" | -
 +
|
 +
| '''{variable}' used outside of binding context.''
 +
|
 +
Occurs when a function-scoped variable (<tt>var</tt>) is treated as if it was block scoped.
 +
|  
 +
|
 
|-
 
|-
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=424204 missing-doc-items]
+
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=424204 missing-doc-items]
 
| Ignore
 
| Ignore
 +
|style="text-align:center;" | -
 +
|
 +
| ''Missing '{a}' tag for '{b}'.''
 
| Flags missing documentation for parameters, returns, throws, etc on function declarations and function expressions when they appear as object properties
 
| Flags missing documentation for parameters, returns, throws, etc on function declarations and function expressions when they appear as object properties
 +
|
 +
|
 
|-
 
|-
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427310 unused-parameters]
 
| Error
 
| Flags parameters in function declarations / expressions if they are not being used
 
|-
 
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=425200 no-mixed-returns]
 
| Error
 
| Flags functions that return more than one kind of item, for example returning String and Object
 
|-
 
!| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428429 missing-nls]
 
| Ignore
 
| Flags String literals that are not properly NLS'd
 
 
|}
 
|}
  
== Rule priority ==
+
== Implementing a new rule ==
Here are the rules we want to support, grouped by priority. Implemented rules are <del>struck out</del>.
+
''This section explains how to implement a new linting rule. For brevity, all paths are given relative to <tt>bundles/org.eclipse.orion.client.javascript/web/</tt> in the client repo.''
  
==== Critical ====
+
First, create the tests and rule:
* [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428433 block-scoped-var]
+
# Create a new <tt>describe("{rule-name}")</tt> block in: <tt>/js-tests/javascript/eslintRuleTests.js</tt>. Add several tests to it.
* <del>eqeqeq</del>
+
# [[#Running the tests|Run the JS bundle tests]] and ensure that your new tests fail.
* <del>no-undef</del>
+
# Implement the actual logic for your rule in <tt>/eslint/lib/load-rules-async.js</tt>.
* <del>no-redeclare</del>
+
# Run the tests again. This time they should all pass.
* <del>no-unused-vars</del>
+
* <del>no-use-before-define</del>
+
  
==== Important ====
+
To get your rule running in the Orion product's validator, there are additional steps:
* guard-for-in
+
# Create strings for the validation message(s) generated by your rule in <tt>/javascript/nls/root/problems.js</tt>.
* [https://bugs.eclipse.org/bugs/show_bug.cgi?id=428429 no-dupe-keys]
+
# Create a short string describing what your rule does in <tt>/javascript/nls/root/messages.js</tt>.
* no-octal
+
# Add an entry to the <tt>orion.core.setting</tt> declaration in <tt>/javascript/plugins/javascriptPlugin.js</tt>. This allows your rule to be configured from the JS validator settings page. Make sure it references the same <tt>nameKey</tt> used in <tt>messages.js</tt>.
* no-with
+
# Add a config entry for your rule to <tt>/javascript/ruleData.js</tt>.
* radix
+
# Add your rule to the #updated() handler in <tt>/javascript/validator.js</tt>.
* <del>[https://bugs.eclipse.org/bugs/show_bug.cgi?id=427930 semi]</del>
+
* <del>[https://bugs.eclipse.org/bugs/show_bug.cgi?id=428040 no-extra-semi]</del>
+
* wrap-iife
+
  
==== Nice to have ====
+
Reload the JS plugin, and your rule should now be configurable from the Settings page, and properly set up for translation too.
* dot-notation
+
* new-cap
+
* new-parens
+
* no-caller
+
* no-comma-dangle
+
* no-implied-eval
+
* no-new-array
+
* no-new-object
+
* no-undef-init
+
* no-unused-expressions
+
* no-wrap-func
+
* use-isnan
+
  
 
== Tests ==
 
== Tests ==
* Every rule needs extensive unit tests
+
* Every rule needs extensive unit tests.
* Unit tests should use Mocha
+
* Unit tests should use [http://mochajs.org Mocha].
 
+
Currently the tests are run from Node.js. They do not run in the browser (yet).
+
 
+
=== Test requirements ===
+
First install [http://nodejs.org/ Node.js]. Then open a console and install Mocha globally:
+
 
+
$ npm install mocha -g
+
 
+
Then from your Orion client repository, run these commands to install eslint's dependencies:
+
 
+
$ cd bundles/org.eclipse.orion.client.javascript/web/eslint/
+
$ npm install
+
  
 
=== Running the tests ===
 
=== Running the tests ===
From the <code>bundles/org.eclipse.orion.client.javascript/web/eslint/</code> directory, simply run <code>npm test</code>:
+
* To run the ESLint tests as part of the main JavaScript tests suite load <tt>{orion-server-url}/javascript/js-tests/JsMochaSuite.html</tt> in your web browser.
 
+
** Click [https://orionhub.org/js-tests/javascript/JsMochaSuite.html here] to see the suite running on [https://orionhub.org orionhub].
$ npm test
+
* To run just the ESLint rule tests, load <tt>{orion-server-url}/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Rule%20Tests</tt> in your browser.
+
** Click [https://orionhub.org/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Rule%20Tests here] to see the suite running on [https://orionhub.org orionhub].
> eslint@0.2.0-dev test c:\Users\mamacdon\code\orion\client\bundles\org.eclipse.orion.client.javascript\web\eslint
+
* To run just the ESLint core tests, load <tt>{orion-server-url}/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Core%20Tests</tt> in your browser.
> bash scripts/test.sh
+
** Click [https://orionhub.org/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Core%20Tests here] to see the suite running on [https://orionhub.org orionhub].
+
* To run only a subset of the tests, add <tt>?grep=ESLint%20Rule%20Tests</tt> onto the test page URL.  
+
  ......................................................................
+
  ...............
+
+
  85 passing (106ms)
+
 
+
To run only a subset of the tests, launch mocha from the command line, passing the test file:
+
 
+
$ mocha tests/lib/rules/semi.js
+
+
  ............
+
+
  12 passing (17ms)
+
 
+
You can also pass an entire directory:
+
 
+
$ mocha tests/lib/rules
+
+
  ......................................................................
+
  ..........
+
+
  80 passing (104ms)
+
 
+
To run only some tests from a file, use the --grep option:
+
 
+
$ mocha tests/lib/rules/semi.js --grep VariableDeclaration
+
+
  .
+
+
  1 passing (5ms)
+
  
See [http://visionmedia.github.io/mocha/#usage Mocha usage options] for more.
+
See [http://mochajs.org/#grep-query Mocha usage options] for more options.
  
 
== User interface ==
 
== User interface ==
 
* <del>Should we have a UI for configuring what rules are active?</del> [https://bugs.eclipse.org/bugs/show_bug.cgi?id=424268 bug 424268].
 
* <del>Should we have a UI for configuring what rules are active?</del> [https://bugs.eclipse.org/bugs/show_bug.cgi?id=424268 bug 424268].
* Should we try to support <code>.eslintrc</code>? This would be an ideal project-scope setting.
+
* Should we try to support <code>.eslintrc</code>? This would be an ideal project-scope setting, and is being tracked in [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461228 bug 461228].
* Should we try to honor equivalent JSLint/JSHint flags when possible? For example <code>/*jslint eqeqeq:false */</code> could disable the eqeqeq rule on a per-file basis.
+
* <del>Should we try to honor equivalent JSLint/JSHint flags when possible? For example <code>/*jslint eqeqeq:false */</code> could disable the eqeqeq rule on a per-file basis.</del>
** This would give compatibility with Orion codebase which uses these flags.
+
** ESLint now has its own syntax for this: <code>/*eslint ..*/</code>, which we are using instead.
** OTOH, eslint now has its own syntax for this: <code>/*eslint ..*/</code>, which we should perhaps use instead.
+
  
 
== i18n ==
 
== i18n ==
We need to support i18n. Pre-req is {{bug|422278}} (orion.edit.validator support for i18n).
+
<del>We need to support i18n. Pre-req is {{bug|422278}} (orion.edit.validator support for i18n).</del>
  
 
[[Category:Orion]]
 
[[Category:Orion]]
 +
[[Category:JavaScript]]

Latest revision as of 17:38, 8 December 2016

Orion 5.0 introduced ESLint as the validator that ships with Orion. This page captures ongoing issues.

Rules

The following sections describe all of the rules currently available in Orion and ones that we plan to add in the future.

To view this table in the same order as the Orion Settings page, hover over the Setting Message column title and press the down arrow to sort.

Potential Programming Problems

These rules report about problems with your code that might have undesired or incorrect results. Warnings from these rules should be addressed.

Rule Default Severity Available Since Setting Message Problem Message Details Quick Fix? Fix All?
no-comma-dangle Ignore 8.0 Trailing commas in object expressions Trailing commas in object expressions are discouraged. Flags trailing commas in object expressions.
no-cond-assign Error 8.0 Assignments in conditional expressions Expected a conditional expression and instead saw an assignment. Flags assignment in an if/while/do..while/for condition.
no-console Ignore 8.0 Discouraged console use in browser code Discouraged use of console in browser-based code. Flags the use of console in browser-based code
no-constant-condition Error 8.0 Constant as conditional expression ... is constant. Flags the use of a constant as a conditional expression
no-const-assign Error 13.0 Disallow modifying variables that are declared using const Discouraged use of constant as a conditional expression. Flags the assignment to a constant variable
no-control-regex Error 11.0 Disallow control characters in regular expressions Unexpected control character in regular expression Control characters are special, invisible characters in the ASCII range 0-31. These characters are rarely used in JavaScript strings so a regular expression containing these characters is most likely a mistake.
no-debugger Warning 6.0 Discouraged 'debugger' statement use debugger' statement use is discouraged. Warns when the debugger keyword is used
no-dupe-keys Error 6.0 Duplicate object keys Duplicate object key '{key}'. Flags object literals that contain the same key more than once.
no-duplicate-case Error 11.0 Duplicate case Duplicate case label. A switch statements with duplicate case labels is normally an indication of a programmer error.
no-empty-block Ignore 7.0 Undocumented empty block Empty block should be removed or commented. Flags an empty block like if (something) { }.
no-empty-character-class Error 11.0 Disallow empty character classes Empty class. Empty character classes in regular expressions do not match anything and can result in code that may not work as intended.
no-extra-boolean-cast Error 11.0 Discourage redundant double negation Redundant double negation in ... In contexts such as an if statement's test where the result of the expression will already be coerced to a Boolean, casting to a Boolean via double negation (!!) is unnecessary.
no-extra-parens Warning 11.0 Discourage redundant parentheses Gratuitous parentheses around expression. This rule restricts the use of parentheses to only where they are necessary. It may be restricted to report only function expressions.
no-extra-semi Warning 5.0 Unnecessary semicolons Unnecessary semicolon. Warns when a semicolon is found where it is not needed
no-fallthrough Error 6.0 Switch case fall-through Switch case may be entered by falling through previous case. If intended, add a new comment //$FALL-THROUGH$ on the line above Flags a fallthrough case within a switch statement, unless it is explicitly commented.
no-invalid-regexp Error 11.0 Invalid regular expressions Invalid flags supplied to RegExp constructor '{${0}}'. or the error message from calling the constructor with the regex This rule validates string arguments passed to the RegExp constructor.
no-irregular-whitespace Ignore 11.0 Report irregular whitespace 'Irregular whitespace not allowed This rule validates all whitespaces
no-negated-in-lhs Error 11.0 Disallow negated left operand of in operator The 'in' expression's left operand is negated. Disallow negated left operand of in operator
no-obj-calls Error 11.0 Disallow global object as function calls '{${0}}' is not a function. ECMAScript provides several global objects that are intended to be used as-is. Some of these objects look as if they could be constructors due their capitalization (such as Math and JSON) but will throw an error if you try to execute them as functions.
no-regex-spaces Error 8.0 Multiple spaces in regular expressions Avoid using multiple spaces in regular expressions. Use ' {${0}}' instead. Flags regular expressions that have two or more subsequent spaces.
no-reserved-keys Ignore 8.0 Reserved words used as property keys Reserved words should not be used as property keys. Checks to see if a JavaScript reserved word is being used as a property key
no-sparse-arrays Warning 8.0 Sparse array declarations Sparse array declarations should be avoided. Flags sparse arrays with null elements like var arr = [1, ,2]
no-unreachable Warning 6.0 Unreachable code Unreachable code. Flags statements that occur after a return, throw, etc.
type-checked-consistent-return Ignore 11.0 Discouraged inconsistent returns Inconsistent return types: (type1) (type2) Warns when a function returns two values with different types.
use-isnan Error 6.0 NaN not compared with isNaN() Use the isNaN function to compare with NaN. Warns when a comparison is done against NaN without using the isNaN function
valid-typeof Error 7.0 Invalid 'typeof' comparison Invalid typeof comparison. Warns when a typeof comparison uses an invalid type.

Best Practices

These rules are not necessarily problem with your code, but are warnings that you might be doing something you probably should not be.

Rule Default Severity Available Since Setting Message Problem Message Details Quick Fix? Fix All?
accessor-pairs Warning 11.0 Getter and setter accessors not in pairs Getter is not present or Setter is not present It's a common mistake in JavaScript to create an object with just a setter for a property but never have a corresponding getter defined for it. Without a getter, you cannot read the property, so it ends up not being used.
check-tern-plugin Warning 12.0 Missing .tern-project plugins entry for environment directive To work in the 'foo' environment, the 'bar' plugin must be running. Warn when the an eslint-env directive specifies a library Orion provides tooling support for, but the library plugin has been disabled in the .tern-project file.
curly Ignore 6.0 Statements not enclosed in braces Statements should be enclosed in braces. Warns when statements should be enclosed in braces, for example if(something) foo();
eqeqeq Warning 5.0 Discouraged '==' use
  • Expected '===' and saw '=='.
  • Expected '!==' and saw '!='.
Warns when == or != is used
missing-requirejs Warning 12.0 'requirejs' plugin missing in AMD environment To use AMD, the 'requirejs' plug-in needs to be running. Flags references to function calls from AMD when the Tern 'requirejs' plugin is not running
no-caller Error 9.0 Discouraged 'arguments.caller' or 'arguments.callee' use arguments.{callee, caller} is deprecated. Flags references to arguments.callee and arguments.caller. Future
no-else-return Warning 11.0 Unnecessary else after return Unexpected 'else' after 'return'. If an if block contains a return statement, the else block becomes unnecessary. Its contents can be placed outside of the block.
no-empty-label Error 11.0 No empty labels Unexpected label "{${0}}" Labeled statements are only used in conjunction with labeled break and continue statements. ECMAScript has no goto statement.
no-eq-null Error 11.0 Disallow null comparisons Use ‘===’ to compare with ‘null’. or Use ‘!==’ to compare with ‘null’. Comparing to null without a type-checking operator (== or !=), can have unintended results as the comparison will evaluate to true when comparing to not just a null, but also an undefined value.
no-extend-native Error 13.0 Disallow extending of native objects '..... prototype is read only, properties should not be added.' Disallows directly modifying the prototype of builtin objects.
no-extra-bind Warning 13.0 Unnecessary 'bind()' use The function binding is unnecessary. Warns about unnecessary use of bind()
no-eval Ignore 6.0 Discouraged 'eval()' use 'eval' function calls are discouraged. Warns when the eval() function is used
no-implicit-coercion Warning 13.0 Disallow the type conversion with shorter notations. use `Boolean(..)` instead., use `...indexOf(".") !== -1` instead., use `Number(..)` instead., use `String(foo)` instead. This rule is aimed to flag shorter notations for the type conversion, then suggest a more self-explanatory notation.
no-implied-eval Ignore 6.0 Discouraged implied 'eval()' use Implicit 'eval' function calls are discouraged. Flags calls to the string-argument form of setTimeout and setInterval, which implicitly perform eval. This rule logic was merged to be part of the no-eval rule.
no-invalid-this Warning 13.0 Discouraged 'this' use outside of classes or class-like objects Unexpected 'this' This rule aims to flag usage of 'this' keywords outside of classes or class-like objects
no-iterator Error 8.0 Discouraged __iterator__ property use Discouraged __iterator__ property use. Flags use of __iterator__ as an identifier name or property key.
no-lone-blocks Ignore 13.0 Discouraged lone block use Block is redundant. or Nested block is redundant. Flags use of unnecessary and potentially confusing blocks at the top level of a script or within other blocks.
no-native-reassign Error 13.0 Disallow reassignment of native objects ... is a read-only native object. This rule flags modifications to read-only global variables
no-new-array Warning 6.0 Discouraged 'new Array()' Use the array literal notation []. Flags new Array(). ESLint calls this rule no-array-constructor
no-new-func Warning 6.0 Discouraged 'new Function()' The Function constructor is eval. Flags new Function().
no-new-object Warning 6.0 Discouraged 'new Object()' Use the object literal notation {}. Flags new Object().
no-new-wrappers Warning 6.0 Discouraged wrapper objects Do not use {String, Number, Boolean, Math, JSON} as a constructor. Flags new applied to any of those.
no-param-reassign Ignore 13.0 Disallow Reassignment of Function Parameters
  • Assignment to function parameter 'bar'.
  • Assignment to property of function parameter 'bar'.
Report parameter reassignment inside functions. Can also report reassignment of parameter's properties.
no-proto Error 9.0 Discouraged __proto__ property use
  • Reserved name '__proto__' should not be assigned.
  • Reserved name '__proto__' should not be used as a key.
Flags use of the property __proto__ as object keys or in assignments
no-redeclare Warning 5.0 Variable re-declarations '{a}' is already defined. Usually results from having two for loops in the same function that share a loop variable declaration like var i=....
no-self-assign Error 11.0 Disallow self assignment '{a}' is assigned to itself. Warns when a variable is being assigned to itself
no-self-compare Error 11.0 Disallow self compare Comparing to itself is potentially pointless. Comparing a variable against itself is usually an error, either an typo or refactoring error. It is confusing to the reader and may potentially introduce a runtime error.
no-shadow Warning 8.0 Variable shadowing '{a}' is already declared in the upper scope. Flags variables that have the same name as a variable declared in an upper scope.
no-shadow-global Warning 9.0 Global shadowing '{a}' shadows a global member. Flags variables that have the same name as a variable declared in the global scope or specified environments.
no-throw-literal Warning 9.0 Literal used in 'throw' Throw an Error instead. Flags code that throws a literal, eg. throw "a problem occurred";
no-undef Error 5.0 Undeclared global reference '{variable}' is not defined.
  • Flags references to a global variable that is not listed in a /*global*/ or /*globals*/ block.
  • Predefined environments (eg. node, browser, amd) can be set in a /*eslint-env*/ block.
no-undef-expression Warning 12.0 Undeclared function reference '{member}' is undefined for '{object}' in {file}. Flags references to a function that is not known to be a property of an object. Will only warn if the object has known properties.
no-undef-init Warning 9.0 Undeclared function reference Avoid explicitly initializing variables to 'undefined'. Avoid initializing variables to undefined.
no-unused-expressions Ignore 13.0 Unused expressions Expected an assignment or function call and instead saw an expression. Flags expressions that have no effect on the running code
no-unused-params Warning 6.0 Unused parameters Parameter '{param}' is not used. Flags parameters in function declarations / expressions if they are not being used
no-unused-vars Warning 5.0 Unused variables
  • '{a}' is unread.
  • '{a}' is read-only.
  • '{a}' is unused.
  • Function '{a}' is unused
Warns when a variable is created and not used (read) or a variable that is read-only is assigned to.

Warns when a function is not used.

no-use-before-define Warning 5.0 Member used before definition '{a}' was used before it was defined. Warns when a variable, function or class is used before it is defined
no-void Ignore 13.0 Disallow use of the void operator. Expected 'undefined' and instead saw 'void'. Discourage the usage of the void operator.
no-with Warning 9.0 Discouraged 'with' statement use Expected an identifier and instead saw 'with'. Treated as fatal parse error in JSLint.
radix Warning 8.0 Missing radix parameter to parseInt() Missing radix parameter. Warns when parseInt() called without the 2nd parameter (radix).
unknown-require Warning 12.0 Validation of the tern settings This library could not be found, type information for it will be incomplete. Validation of the tern settings for libraries.
yoda Ignore 13.0 Require or disallow Yoda Conditions
  • Expected literal to be on the right side of ...
  • Expected literal to be on the left side of ...
Enforce consistent style of conditions which compare a variable to a literal value.

Code Style

These rules are not problems in any way but will warn based on certain accepted styles for coding.

Rule Default Severity Available Since Setting Message Problem Message Details Quick Fix? Fix All?
missing-doc Ignore 5.0 Missing JSDoc Missing documentation for function '{name}'. Flags missing documentation nodes on function declarations and function expressions when they appear as object properties
missing-nls Ignore 9.0 Non-externalized string literals (missing $NON-NLS$ tag) Non-externalized string literal '{a}'. Flags String literals that are not properly NLS'd
new-parens Error 6.0 Missing parentheses in constructor call Missing parentheses invoking constructor. Flags new Whatever
no-mixed-spaces-and-tabs Ignore 11.0 Mixed spaces and tabs Irregular whitespace not allowed. Invalid or irregular whitespace causes issues with ECMAScript 5 parsers and also makes code harder to debug in a similar nature to mixed tabs and spaces.
no-jslint Warning 7.0 Unsupported environment directive The 'jslint' directive is unsupported, please use eslint-env. Flags use of the /* jslint */ directive Future
no-trailing-spaces Ignore 13.0 Unsupported environment directive Trailing spaces not allowed. Flags any trailing spaces
quotes Ignore 13.0 Validate which quotes should be used (either single, double or backtick (es6 only)) Strings must use doublequote., Strings must use singlequote., Strings must use backtick. Warns when a quote is not the expected one
semi Warning 5.0 Missing semicolons Missing semicolon. Warns when a semicolon should be used but is not
unnecessary-nls Ignore 11.0 Unnecessary $NON-NLS$ tags Unnecessary $NON-NLS$ tag. Flags $NON-NLS$ comments that are not needed to exclude a string literal

Future Implementations

Rules that are being considered for inclusion or were implemented but removed.

Rule Default Severity Available Since Setting Message Problem Message Details Quick Fix? Fix All?
block-scoped-var Error - '{variable}' used outside of binding context.

Occurs when a function-scoped variable (var) is treated as if it was block scoped.

missing-doc-items Ignore - Missing '{a}' tag for '{b}'. Flags missing documentation for parameters, returns, throws, etc on function declarations and function expressions when they appear as object properties

Implementing a new rule

This section explains how to implement a new linting rule. For brevity, all paths are given relative to bundles/org.eclipse.orion.client.javascript/web/ in the client repo.

First, create the tests and rule:

  1. Create a new describe("{rule-name}") block in: /js-tests/javascript/eslintRuleTests.js. Add several tests to it.
  2. Run the JS bundle tests and ensure that your new tests fail.
  3. Implement the actual logic for your rule in /eslint/lib/load-rules-async.js.
  4. Run the tests again. This time they should all pass.

To get your rule running in the Orion product's validator, there are additional steps:

  1. Create strings for the validation message(s) generated by your rule in /javascript/nls/root/problems.js.
  2. Create a short string describing what your rule does in /javascript/nls/root/messages.js.
  3. Add an entry to the orion.core.setting declaration in /javascript/plugins/javascriptPlugin.js. This allows your rule to be configured from the JS validator settings page. Make sure it references the same nameKey used in messages.js.
  4. Add a config entry for your rule to /javascript/ruleData.js.
  5. Add your rule to the #updated() handler in /javascript/validator.js.

Reload the JS plugin, and your rule should now be configurable from the Settings page, and properly set up for translation too.

Tests

  • Every rule needs extensive unit tests.
  • Unit tests should use Mocha.

Running the tests

  • To run the ESLint tests as part of the main JavaScript tests suite load {orion-server-url}/javascript/js-tests/JsMochaSuite.html in your web browser.
  • To run just the ESLint rule tests, load {orion-server-url}/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Rule%20Tests in your browser.
  • To run just the ESLint core tests, load {orion-server-url}/js-tests/javascript/JsMochaSuite.html?grep=ESLint%20Core%20Tests in your browser.
  • To run only a subset of the tests, add ?grep=ESLint%20Rule%20Tests onto the test page URL.

See Mocha usage options for more options.

User interface

  • Should we have a UI for configuring what rules are active? bug 424268.
  • Should we try to support .eslintrc? This would be an ideal project-scope setting, and is being tracked in bug 461228.
  • Should we try to honor equivalent JSLint/JSHint flags when possible? For example /*jslint eqeqeq:false */ could disable the eqeqeq rule on a per-file basis.
    • ESLint now has its own syntax for this: /*eslint ..*/, which we are using instead.

i18n

We need to support i18n. Pre-req is bug 422278 (orion.edit.validator support for i18n).

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