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Difference between revisions of "Orion/ESLint"
(→Best Practices) |
(→Potential Programming Problems: Fix bad formatting on no-irregular-whitespace rule) |
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| ''Expected a conditional expression and instead saw an assignment.'' | | ''Expected a conditional expression and instead saw an assignment.'' | ||
| Flags assignment in an <code>if/while/do..while/for</code> condition. | | Flags assignment in an <code>if/while/do..while/for</code> condition. | ||
− | | style="text-align:center;" | | + | | style="text-align:center;" | ✔ |
− | | | + | |style="text-align:center;" | ✔ |
|- | |- | ||
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455371 no-console] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455371 no-console] | ||
Line 51: | Line 51: | ||
|style="text-align:center;"| 8.0 | |style="text-align:center;"| 8.0 | ||
|Constant as conditional expression | |Constant as conditional expression | ||
− | | '' | + | | ''...'' is constant. |
| Flags the use of a constant as a conditional expression | | Flags the use of a constant as a conditional expression | ||
+ | | | ||
+ | | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455680 no-const-assign] | ||
+ | | Error | ||
+ | |style="text-align:center;"| 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 | ||
| | | | ||
| | | | ||
Line 114: | Line 123: | ||
|style="text-align:center;"| 11.0 | |style="text-align:center;"| 11.0 | ||
|Discourage redundant double negation | |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. | | 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;" | | ||
Line 152: | Line 161: | ||
| ''Invalid flags supplied to RegExp constructor '{${0}}'.'' or the error message from calling the constructor with the regex | | ''Invalid flags supplied to RegExp constructor '{${0}}'.'' or the error message from calling the constructor with the regex | ||
| This rule validates string arguments passed to the RegExp constructor. | | 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] | ||
+ | | Ignore | ||
+ | |style="text-align:center;"| 11.0 | ||
+ | | Report irregular whitespace | ||
+ | | '''Irregular whitespace not allowed'' | ||
+ | | This rule validates all whitespaces | ||
|style="text-align:center;" | | |style="text-align:center;" | | ||
|style="text-align:center;" | | |style="text-align:center;" | | ||
Line 183: | Line 201: | ||
|- | |- | ||
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455354 no-reserved-keys] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=455354 no-reserved-keys] | ||
− | | | + | | Ignore |
|style="text-align:center;"| 8.0 | |style="text-align:center;"| 8.0 | ||
|Reserved words used as property keys | |Reserved words used as property keys | ||
Line 261: | Line 279: | ||
|style="text-align:center;" | | |style="text-align:center;" | | ||
|- | |- | ||
− | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id= | + | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=490332 check-tern-plugin] |
− | | | + | | Warning |
− | |style="text-align:center;" | | + | |style="text-align:center;" | 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 | + | | 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= | + | | style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=490332 ✔] |
| style="text-align:center;" | | | style="text-align:center;" | | ||
|- | |- | ||
Line 289: | Line 307: | ||
| style="text-align:center;" | ✔ | | style="text-align:center;" | ✔ | ||
| style="text-align:center;" | ✔ | | style="text-align:center;" | ✔ | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=493019 missing-requirejs] | ||
+ | | Warning | ||
+ | |style="text-align:center;" | 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 | ||
+ | | 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] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=460976 no-caller] | ||
Line 305: | Line 332: | ||
| ''Unexpected '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. | | 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:center;" | | |style="text-align:center;" | | ||
|- | |- | ||
Line 325: | Line 352: | ||
|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: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] | ||
+ | | Error | ||
+ | |style="text-align:center;"| 13.0 | ||
+ | | Disallow extending of native objects | ||
+ | | '..... 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] | ||
+ | | Warning | ||
+ | |style="text-align:center;" | 13.0 | ||
+ | |Unnecessary 'bind()' use | ||
+ | | ''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] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429702 no-eval] | ||
Line 333: | Line 378: | ||
| Warns when the <code>eval()</code> function is used | | 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] | ||
+ | | Warning | ||
+ | |style="text-align:center;" | 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. | ||
+ | | | ||
| | | | ||
|- | |- | ||
Line 341: | Line 395: | ||
| ''Implicit 'eval' function calls are discouraged.'' | | ''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. | | 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 | ||
| | | | ||
| | | | ||
Line 350: | Line 413: | ||
| ''Discouraged __iterator__ property use.'' | | ''Discouraged __iterator__ property use.'' | ||
| Flags use of <code>__iterator__</code> as an identifier name or property key. | | Flags use of <code>__iterator__</code> as an identifier name or property key. | ||
+ | | | ||
+ | | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486761 no-lone-blocks] | ||
+ | | Ignore | ||
+ | |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;" | | ||
+ | | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486760 no-native-reassign] | ||
+ | | Error | ||
+ | |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 | ||
| | | | ||
| | | | ||
Line 387: | Line 468: | ||
| 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: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] | ||
+ | | Ignore | ||
+ | |style="text-align:center;" | 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. | ||
+ | | | ||
| | | | ||
|- | |- | ||
Line 406: | Line 498: | ||
| '''{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;" | | + | | style="text-align:center;" | ✔ |
| | | | ||
|- | |- | ||
Line 413: | Line 505: | ||
|style="text-align:center;" | 11.0 | |style="text-align:center;" | 11.0 | ||
|Disallow self assignment | |Disallow self assignment | ||
− | | '' | + | | '''{a}' is assigned to itself.'' |
| Warns when a variable is being assigned to itself | | Warns when a variable is being assigned to itself | ||
| 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 ✔] | ||
Line 451: | Line 543: | ||
| ''Throw an Error instead.'' | | ''Throw an Error instead.'' | ||
| Flags code that throws a literal, eg. <code>throw "a problem occurred";</code> | | Flags code that throws a literal, eg. <code>throw "a problem occurred";</code> | ||
− | |||
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| style="text-align:center;" | ✔ | | style="text-align:center;" | ✔ | ||
| style="text-align:center;" | | | style="text-align:center;" | | ||
Line 477: | Line 558: | ||
|- | |- | ||
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461852 no-undef-expression] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461852 no-undef-expression] | ||
− | | | + | | Warning |
|style="text-align:center;" | 12.0 | |style="text-align:center;" | 12.0 | ||
− | |Undeclared | + | |Undeclared function reference |
− | | '''{member}' is | + | | '''{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. | + | | 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:center;" | | | style="text-align:center;" | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461852 no-undef-init] | ||
+ | | Warning | ||
+ | |style="text-align:center;" | 9.0 | ||
+ | | Undeclared function reference | ||
+ | | ''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] | ||
+ | | Ignore | ||
+ | |style="text-align:center;" | 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 | ||
+ | | 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] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427310 no-unused-params] | ||
Line 513: | Line 612: | ||
|Member used before definition | |Member used before definition | ||
| '''{a}' was used before it was defined.'' | | '''{a}' was used before it was defined.'' | ||
− | | Warns when a variable | + | | 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] | ||
+ | | Ignore | ||
+ | |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] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=461854 no-with] | ||
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| 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: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 | ||
+ | | Warning | ||
+ | |style="text-align:center;" | 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. | ||
+ | | style="text-align:center;" | ✔ | ||
+ | | style="text-align:center;" | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486754 yoda] | ||
+ | | Ignore | ||
+ | |style="text-align:center;" | 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. | ||
+ | | | ||
+ | | | ||
|- | |- | ||
|} | |} | ||
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| style="text-align:center;" | ✔ | | style="text-align:center;" | ✔ | ||
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486126 ✔] | | style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=486126 ✔] | ||
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|- | |- | ||
!style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429801 new-parens] | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=429801 new-parens] | ||
Line 603: | Line 722: | ||
| style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=453322 Future] | | style="text-align:center;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=453322 Future] | ||
| | | | ||
+ | |- | ||
+ | !style="text-align:left;"| [https://bugs.eclipse.org/bugs/show_bug.cgi?id=500436 no-trailing-spaces] | ||
+ | | Ignore | ||
+ | |style="text-align:center;" | 13.0 | ||
+ | | 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)) | ||
+ | | ''Strings must use doublequote.'', ''Strings must use singlequote.'', ''Strings must use backtick.'' | ||
+ | | Warns when a quote is not the expected one | ||
+ | | style="text-align:center;" | ✔ | ||
+ | | style="text-align:center;" | ✔ | ||
|- | |- | ||
!style="text-align:left;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427930 semi] | !style="text-align:left;" | [https://bugs.eclipse.org/bugs/show_bug.cgi?id=427930 semi] | ||
Line 610: | Line 747: | ||
| ''Missing semicolon.'' | | ''Missing semicolon.'' | ||
| Warns when a semicolon should be used but is not | | 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;" | ✔ | ||
| style="text-align:center;" | ✔ | | style="text-align:center;" | ✔ | ||
Line 646: | Line 792: | ||
| 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 | ||
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[[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.
Contents
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 |
|
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 |
|
Report parameter reassignment inside functions. Can also report reassignment of parameter's properties. | ||
no-proto | Error | 9.0 | Discouraged __proto__ property use |
|
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. |
|
✔ | |
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 |
|
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 |
|
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:
- Create a new describe("{rule-name}") block in: /js-tests/javascript/eslintRuleTests.js. Add several tests to it.
- Run the JS bundle tests and ensure that your new tests fail.
- Implement the actual logic for your rule in /eslint/lib/load-rules-async.js.
- 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:
- Create strings for the validation message(s) generated by your rule in /javascript/nls/root/problems.js.
- Create a short string describing what your rule does in /javascript/nls/root/messages.js.
- 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.
- Add a config entry for your rule to /javascript/ruleData.js.
- 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.
- ESLint now has its own syntax for this:
i18n
We need to support i18n. Pre-req is bug 422278 (orion.edit.validator support for i18n).