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Orion/ESLint
Orion 5.0 will replace our current JSLint validator with ESLint. This page captures ongoing issues.
Rules
Here's a table showing the equivalent validation rules in JSLint and ESLint. Rules that JSLint does not support are marked as Unsupported.
ESLint rule | JSLint option | JSLint message | Details |
---|---|---|---|
block-scoped-var | Always on | '{variable}' is already defined. |
|
brace-style | Unsupported | ||
camelcase | Unsupported | ||
complexity | Unsupported | ||
consistent-this | Unsupported | ||
curly | Always on |
|
|
dot-notation | sub | {a} is better written in dot notation. | |
eqeqeq | eqeqeq or eqeq |
|
|
guard-for-in | forin | The body of a for in should be wrapped in an if statement to filter unwanted properties from the prototype.
| |
max-depth | Unsupported | Enforces max depth of nested blocks within a function. | |
max-len | maxlen | Line too long. | Enforces a maximum line length. |
max-params | Unsupported | ||
max-statements | Unsupported | ||
new-cap | newcap | A constructor name should start with an uppercase letter. | |
new-parens | Always on | Missing '()' invoking a constructor. | Flags new Whatever
|
no-alert | devel | '{alert, confirm, prompt}' is not defined. | |
no-bitwise | bitwise | Unexpected use of '{operator}'. | JSLint disallows bitwise ops by default. |
no-caller | Unsupported | Flags references to arguments.callee and arguments.caller .
| |
no-catch-shadow | Always on | '{a}' is already defined. |
|
no-comma-dangle | Always on | Unexpected comma. | Flags trailing commas in object literals. |
no-cond-assign | Unsupported | Flags assignment in an if/while/do..while/for condition.
| |
no-console | devel | ||
no-control-regex | Unsupported | Flags control characters (U+0000–U+001F and U+007F) within the source argument to the RegExp constructor. | |
no-debugger | debug | All 'debugger' statements should be removed. | |
no-delete-var | Always on | Expected '.' and instead saw ';'. | Flags an attempt to delete a local variable.
|
no-div-regex | Always on | A regular expression literal can be confused with '/='. | Flags a regex literal starting with /=
|
no-dupe-keys | Always on | Duplicate key '{a}'. | Flags object literals that contain the same key more than once. |
no-else-return | Unsupported | Flags an else appearing after an if that contains a return .
| |
no-empty-class | Always on | Empty class. | Flags an empty character class [] within a regular expression.
|
no-empty-label | Always on | Label '{a}' on statement. | Flags a labeled statement that is not a switch , for , or while .
|
no-empty | Unsupported | Flags an empty block like if (something) { } .
| |
no-eq-null | Always on | Use '===' to compare with 'null'. | JSLint produces a similar warning when comparing against undefined .
|
no-eval | evil | eval is evil. | |
no-ex-assign | Always on | Do not assign to the exception parameter. | |
no-extra-semi | Always on | Unnecessary semicolon. | |
no-fallthrough | Unsupported | Flags a fallthrough case within a switch statement, unless it is explicitly commented.
| |
no-floating-decimal | Always on | A {leading, trailing} decimal point can be confused with a dot: '{n}'. | Flags numeric literals that have a leading or trailing decimal point. |
no-func-assign | Unsupported | Flags assignment to a variable that's already bound to a FunctionExpression .
| |
no-global-strict | Unsupported | Flags "use strict" applied to the entire Program.
| |
no-implied-eval | Always on | Implied eval is evil. Pass a function instead of a string. | Flags calls to the string-argument form of setTimeout and setInterval , which implicitly perform eval .
|
no-iterator | Always on | Reserved name '__iterator__'. | Flags use of __iterator__ as an identifier name or property key. |
no-label-var | Always on | '{label}' is already defined. | Flags labels that collide with an identifier. |
no-loop-func | Always on | Don't make functions within a loop. | |
no-mixed-requires | Flags Node.js require() s that mix different types of requires (core, module, file, computed).
| ||
no-multi-str | Flags use of ES5 multiline string literals. | ||
no-native-reassign | Always on |
|
Flags an attempt to reassign a native object like Math , Array, undefined , etc.
|
no-negated-in-lhs | Unsupported |
| |
no-new-array | Always on | Use the array literal notation []. | Flags new Array() .
|
no-new-func | Always on | The Function constructor is eval. | |
no-new-object | Always on | Use the object literal notation {}. | Flags new Object() .
|
no-new-wrappers | Do not use {String, Number, Boolean, Math, JSON} as a constructor. | Flags new applied to any of those.
| |
no-new | Always on | Do not use 'new' for side effects. | Flags uses of new operator in an expression that is not assigned to anything.
|
no-obj-calls | Partial support | Math is not a function.. |
|
no-octal-escape | Always on | Bad escapement. | Flags octal escapes in strings, for example var x = "Copyright \251";
|
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 |
| |
no-proto | Always on |
|
Treated as a fatal parse error in JSLint. |
no-redeclare | Always on | '{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-return-assign | Unsupported |
| |
no-script-url | Always on | Script URL. |
|
no-self-compare | Unsupported | Flags comparisons where the left- and right-hand sides are the same. | |
no-shadow | Unsupported | Flags variables that have the same name as a variable declared in an outer scope. | |
no-spaced-func | |||
no-sync | stupid | Unexpected sync method: '{a}'. |
|
no-ternary | Unsupported | Flags any use of the ternary operator cond ? thenExpr : elseExpr
| |
no-undef-init | Always on | It is not necessary to initialize '{variable}' to 'undefined'. | |
no-undef | undef | '{variable}' is not defined. |
|
no-underscore-dangle | nomen | Dangling '_' | |
no-unreachable | Always on | Unreachable '{statement}' after '{control flow statement}'. | Flags statements that occur after a return , throw , etc.
|
no-unused-expressions | Always on | 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. |
no-unused-vars | Always on | Function declares unused variable '{a}'. (Orion) | Newer JSlint versions have an unparam option which works similarly. |
no-use-before-define | Always on | '{a}' was used before it was defined. | |
no-with | Always on | Expected an identifier and instead saw 'with'. | 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. (function fun(){})
|
one-var | onevar | Too many var statements. | Allows only 1 var statement per function.
|
quote-props | Unsupported | Requires object literal keys to be quoted with " or '. | |
quotes | Unsupported | Flags any use of single or double quote marks, depending on setting. | |
radix | Always on | Missing radix parameter. | Affects parseInt(). |
regex-spaces | Always on | Spaces are hard to count. Use {n}. | |
semi | Always on | Missing semicolon. | |
strict | strict | Flags any code that lacks the "use strict" pragma.
| |
unnecessary-strict | Unsupported | Flags "use strict" on a function when the entire Program is already in strict mode.
| |
use-isnan | Always on | Use the isNaN function to compare with NaN. | |
wrap-iife | immed |
|
Flags missing parens on immediately-invoked functions, eg. function(){ console.log('hi'); }();
|
wrap-regex | Always on | Wrap the /regexp/ literal in parens to disambiguate the slash operator. |
Rule priority
Here are the rules we want, grouped by priority:
Critical
- no-undef
- eqeqeq
- block-scoped-var
- no-redeclare
Important
- guard-for-in
- no-unused-vars
- no-dupe-keys
- no-octal
- radix
- wrap-iife
Nice to have
- 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
- semi