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This page tries to track ongoing documentation work in the MDN JavaScript section. Feel free to contribute!
Summary
| Pages | No tags | Needs* tags | Missing tags | Editorial reviews | Technical reviews | Outdated pages | Dev-doc-needed bugs | Documentation requests |
|---|---|---|---|---|---|---|---|---|
| 885 | 0 (0%) | 0 (0%) | 0 (0%) | 48 (6%) | 36 (5%) | 43 (5%) | 0 (0%) | 65 (8%) |
See also localization status of this section.
Editorial reviews
Found 48 pages. Learn more about how to do an editorial review.
- A re-introduction to JavaScript (JS tutorial)
- Concurrency model and Event Loop
- Equality comparisons and sameness
- Inheritance and the prototype chain
- Introduction to using XPath in JavaScript
- Indexed collections
- Keyed collections
- Numbers and dates
- JavaScript data types and data structures
- Spread syntax
- this
- Functions
- Arguments object
- Arrow functions
- getter
- Standard built-in objects
- Array
- Array.prototype.concat()
- Array.prototype.sort()
- Array.prototype.values()
- Date
- Date.prototype.setHours()
- Error
- Function
- Generator
- Intl.DateTimeFormat
- JSON
- JSON.stringify()
- Math
- Math.hypot()
- Number
- Object.getOwnPropertyNames()
- handler.apply()
- RegExp
- Set
- Set.prototype.forEach()
- Set.prototype.values()
- String
- String.prototype.concat()
- String.prototype.endsWith()
- WeakMap
- eval()
- for...in
- for...of
- Strict mode
- JavaScript shells
- Memory Management
- New in JavaScript
Technical reviews
Found 36 pages. Learn more about how to do a technical review.
- Closures
- Using promises
- Destructuring assignment
- Arrow functions
- getter
- ReferenceError: reference to undefined property "x"
- Standard built-in objects
- Array.prototype.copyWithin()
- Array.prototype.filter()
- Array.prototype.find()
- Array.prototype.includes()
- Array.prototype.indexOf()
- Array.prototype.reduce()
- Array.prototype.some()
- Date.parse()
- Generator
- Generator.prototype.next()
- JSON.stringify()
- Map.prototype
- Map.prototype[@@iterator]()
- Math.round()
- Math.sqrt()
- Object.create()
- Object.entries()
- Object.freeze()
- Promise.all()
- Promise.reject()
- RegExp
- Set.prototype.forEach()
- String.prototype.concat()
- String.prototype.includes()
- async function
- block
- for...of
- Template literals
- New in JavaScript 1.8.1
Outdated pages
Found 43 pages. These pages haven't been updated in over a year. Outdated pages can have problems with both content and format. Look at these pages and consider: Is this page talking about the Web of today? Does it look consistent with newer pages in this topic area? If not, make any needed changes.
- Differential inheritance in JavaScript
539 days old - Index
504 days old - Deprecated and obsolete features
519 days old - JavaScript error reference
462 days old - Error: Permission denied to access property "x"
379 days old - RangeError: argument is not a valid code point
661 days old - RangeError: invalid array length
661 days old - RangeError: precision is out of range
661 days old - RangeError: radix must be an integer
396 days old - RangeError: repeat count must be less than infinity
661 days old - RangeError: repeat count must be non-negative
661 days old - ReferenceError: deprecated caller or arguments usage
396 days old - ReferenceError: invalid assignment left-hand side
646 days old - SyntaxError: "use strict" not allowed in function with non-simple parameters
396 days old - SyntaxError: JSON.parse: bad parsing
396 days old - SyntaxError: Malformed formal parameter
396 days old - SyntaxError: missing ) after argument list
396 days old - SyntaxError: missing ; before statement
396 days old - SyntaxError: missing ] after element list
396 days old - SyntaxError: missing } after property list
645 days old - SyntaxError: redeclaration of formal parameter "x"
396 days old - SyntaxError: return not in function
396 days old - SyntaxError: test for equality (==) mistyped as assignment (=)?
654 days old - SyntaxError: unterminated string literal
396 days old - TypeError: "x" has no properties
651 days old - TypeError: "x" is not a constructor
396 days old - TypeError: More arguments needed
646 days old - TypeError: invalid Array.prototype.sort argument
396 days old - TypeError: property "x" is non-configurable and can't be deleted
396 days old - TypeError: variable "x" redeclares argument
396 days old - Warning: -file- is being assigned a //# sourceMappingURL, but already has one
649 days old - Warning: unreachable code after return statement
661 days old - JavaScript properties index
763 days old - Transitioning to strict mode
396 days old - JavaScript technologies overview
406 days old - ECMAScript 5 support in Mozilla
424 days old - New in JavaScript 1.1
779 days old - New in JavaScript 1.2
779 days old - New in JavaScript 1.3
779 days old - New in JavaScript 1.4
779 days old - New in JavaScript 1.6
703 days old - New in JavaScript 1.8
779 days old - The performance hazards of [[Prototype]] mutation
689 days old
Documentation requests
Found 65 bugs. Documentation request bugs can contain various kinds work related to MDN pages. Read through the bug and ask questions in the bug if in doubt.
| Bug | Summary |
|---|---|
| 1179881 | Write a JS error reference |
| 1201380 | Examples and text don't match up in "details of the object model" page |
| 1204224 | Unclear explanation in "Working With Objects" tutorial |
| 1238394 | Improve Regex docs for capturing groups |
| 1243496 | The function declaration and function expression documentation is incorrect |
| 1245977 | MathML fallback: square root is not displayed correctly |
| 1275816 | Explain how |this| value is calculated in call expression, and the difference between `foo[prop]()` and `func = foo[prop], func()` |
| 1281696 | iterating with let in for-loops |
| 1286628 | Object.prototype.constructor is not a reference to the constructor of the prototype |
| 1294338 | charCodeAt and codePointAt in String documentation seem almost backwards |
| 1301501 | polyfill uses != to check typeof assign to "function" vs !== |
| 1303603 | Clarify that RegExp.prototype.exec() returns a special array |
| 1305261 | Async Functions/Await Documentation |
| 1307755 | Given for..of example needs some explanation, not self-explaining |
| 1309784 | Add Cyclomatic Complexity |
| 1318620 | Slightly misleading example |
| 1318933 | Description of `Object.keys` outdated because it does not return symbol keys |
| 1319979 | Equality comparisons |
| 1322844 | Tagged template literals example does not illustrate point being made |
| 1324194 | Incorrect description for example summary found on array.prototype.filter() page (JSON example) |
| 1325251 | The Math.sign() polyfill contains two type conversions |
| 1334000 | Polyfill example does not detect NaN |
| 1340310 | How does the Cache interface handle cookies? |
| 1343142 | Clarify that Array.prototype.sort() sorts in increasing order |
| 1346500 | The result of the polyfill doesn't meet the result of firefox. |
| 1347496 | Inaccurate information in a code snippet |
| 1352856 | continue statement, example 2. |
| 1357343 | Console.table example does not work as expected |
| 1359860 | Make /W special character regex more clear |
| 1360102 | About the global property with "var" in MDN. |
| 1360661 | Document for Array.from provides a polyfill that cannot create array from a Set |
| 1361299 | mixin replace jQuery.extend with Object.assign |
| 1363684 | tip faster js offsetwith |
| 1365288 | Map.get/set documentation is lacking information |
| 1367757 | Should String.prototype.substr be marked as deprecated? |
| 1371716 | Syntax example provided is incomplete / incorrect |
| 1372019 | Filter the javascript docs on ES version support |
| 1372390 | Promise.all returns already-resolved promises for any combination of non-promises and resolved promises. |
| 1374016 | A consistency issue: different parts of MDN have links where in other parts they're buttons |
| 1376223 | "Promise" Advance Example CodePen Has a Bug |
| 1385876 | Threading coverage on MDN |
| 1389206 | I would like to contribue to progrssive apps section by adding a new sub-article about how to build progressive apps with Angular 2+ |
| 1393872 | Document JavaScript modules |
| 1394123 | Property Accessors: No mention of what happens when a property is not present on an object |
| 1394569 | Array.prototype.filter polyfill compares result of typeof operator to "Function" instead of "function" |
| 1395257 | JS sidebar macros don't interact well with A/B testing framework |
| 1398923 | Bad link |
| 1401192 | List support for proper stacktrace in the compat table. |
| 1401753 | Promise, advanced example, code comment incorrect |
| 1405611 | Create a page on property descriptors and flags |
| 1408616 | Re-Introduction to JavaScript - Functions: hiding local variables |
| 1408621 | Re-Introduction to JavaScript - Functions: confusing use of fullName(); |
| 1408998 | More examples in Array.prototype.reduce |
| 1411233 | Document XMLHttpRequestEventTarget.ontimeout |
| 1412101 | Discussion of "boolean operator" should be clarified or deleted |
| 1414088 | Glossary entry for Symbol too detailed; move it into the JavaScript Guide, which doesn't say much |
| 1415201 | Update documentation for missing semicolon. |
| 1419710 | Array.prototype.sort confusing |
| 1424040 | Add glossary entries for weak and strong references; update WeakMap and WeakSet docs to link to them |
| 1424211 | Error in comment for calls to function add1 and add2 |
| 1427812 | Incorrect Polyfill function ArrayBuffer.transfer() |
| 1431238 | Description of Map states that it "...will only map to the object's insertion order—which is random and not ordered". This is incorrect since ES6 |
| 1433831 | Process described on page doesn't work any more. |
| 1442950 | Broken link at Event.bubbles page |
| 1443030 | The expression "execution context" is misleading. |
Browse as bug list.
Localizations
Please help us to localize this documentation into different languages. Read more about how to translate.
| Language | Pages | Translated | Translations up to date |
|---|---|---|---|
| af | 873 | 0 (0%) | 0 (0%) |
| bn-BD | 873 | 34 (3%) | 1 (2%) |
| ca | 873 | 321 (36%) | 0 (0%) |
| de | 885 | 493 (55%) | 352 (71%) |
| es | 873 | 396 (45%) | 57 (14%) |
| fa | 873 | 19 (2%) | 2 (10%) |
| fr | 884 | 884 (100%) | 884 (100%) |
| id | 873 | 102 (11%) | 3 (2%) |
| it | 873 | 139 (15%) | 14 (10%) |
| ja | 882 | 847 (96%) | 122 (14%) |
| kab | 873 | 2 (0%) | 1 (50%) |
| ko | 873 | 379 (43%) | 44 (11%) |
| nl | 873 | 62 (7%) | 8 (12%) |
| pl | 873 | 298 (34%) | 9 (3%) |
| pt-BR | 873 | 365 (41%) | 53 (14%) |
| pt-PT | 873 | 42 (4%) | 2 (4%) |
| ro | 873 | 22 (2%) | 1 (4%) |
| ru | 873 | 562 (64%) | 62 (11%) |
| zh-CN | 883 | 758 (85%) | 213 (28%) |
Structure of the MDN JavaScript docs
| # | Chapter | Pages | Priority | Notes |
|---|---|---|---|---|
| 0 | Value & function properties in the global scope | 16 | 1 | Complete. |
| 1 | Object | 40 | 1 |
Complete. |
| 2 | Function | 14 | 1 | Complete. |
| 3 | Array | 38 | 1 | Complete. |
| 4 | String | 50 | 1 | Complete. |
| 5 | Boolean | 5 | 1 | Complete. |
| 6 | Number | 24 | 1 |
Complete. |
| 7 | Math | 44 | 1 | Complete. |
| 8 | Date | 53 | 1 | Complete. |
| 9 | RegExp | 21 | 1 | Complete. |
| 10 |
Error |
24 | 4 | Complete. |
| 11 | JSON | 3 | 1 | Complete. |
| 12 | Intl Intl.Collator Intl.DateTimeFormat Intl.NumberFormat |
16 | 2 | Complete. |
| 13 | Map | 13 | 2 | Complete. |
| 14 | WeakMap | 7 | 2 | Complete. |
| 15 | Set | 11 | 2 | Complete. |
| 16 | SIMD
Float32x4 |
3 | In Nightly. Spec in flux. | |
| 17 | WeakSet | 6 | 2 | Complete. |
| 18 | Proxy | 17 | 3 | Complete. |
| 19 | Reflect | 15 | 3 | Complete. |
| 20 | Generator (legacy and ES2015) Iterator StopIteration GeneratorFunction |
8 | 2 | Complete. |
| 21 | ArrayBuffer (6)DataView (21)TypedArray (34 [+ 3])Float32ArrayFloat64ArrayInt16ArrayInt32ArrayInt8ArrayUint16ArrayUint32ArrayUint8ArrayUint8ClampedArray |
73 | 2 | Missing pages:
|
| 22 | Promise | 8 | 1 | Complete. |
| 23 | Symbol | 9 | 2 |
Missing pages:
|
| 24 | ParallelArray | 1 | 5 | Complete. |
| 25 | Atomics SharedArrayBuffer |
17 | 4 | Preffed off. Spec in flux. |
| 26 | Expressions & Operators | 29 | 1 | Complete. |
| 27 | Statements & Declarations | 27 | 1 | Complete. |
| 28 | Functions | 11 | 1 |
Complete. |
| 29 | Classes | 4 | 1 | Complete. |
| 30 | JavaScript Guide | 15 | 1 |
|
| 31 | New in JavaScript | 15 | 4 |
Complete. |
| 32 | JavaScript error reference | 36 | 3 | Explains error messages (v8, Chakra). So those people searching for errors will find guidance. |
| 33 | Articles/Tutorials/Misc | 17 |
3 |
|
| 34 | Meta pages | 9 | 4 |
Other tasks to do
- Go through Firefox release notes for developers and site compat notes and make sure JS changes are documented properly in the references.
- Make sure our compat tables are up to date by also going through bug trackers of other open source browsers (e.g. WebKit, Blink)
- Write a changelog for Chrome JavaScript releases like we have for Firefox. Same for other browsers/node.js?
- Meta article about how to document in the JS MDN area.
- Write more JavaScript error documentation: The list of errors which have no mdn pages link corresponds to SpiderMonkey error code which are reported to the devtool console which do not have any corresponding MDN pages.
Tagging standard
- Pages in the JavaScript/ page tree should at least have the tag "JavaScript".
- For methods belonging to an object, the name of the Object should be added (e.g.
String.fromCharCodeshould have "String"). - Methods should have "Method" and properties need a "Property" tag. All prototype members have the "prototype" tag.
- Features added in a new ECMAScript version have the tags "ECMAScript6" and "ECMAScript 2015" or later versions/years.
- The Experimental tag should only be used with new features where the standard in not yet finalized (e.g. in a strawman proposal) and the feature is in a Nightly version or behind a preference.
- Features are Deprecated if their usage is discouraged and are Obsolete if they have been removed from engines.
- If pages need any type of work, a "Needs*" tag should be added (see above).
Specifications
The following specifications are taken under consideration for this project:
| Specification | Status |
|---|---|
| ECMAScript 5.1 (ECMA-262) | Standard |
| ECMAScript 2015 (6th Edition, ECMA-262) | Standard |
| ECMAScript Latest Draft (ECMA-262) | Draft |
| ECMAScript Internationalization API 1.0 (ECMA-402) | Standard |
| ECMAScript Internationalization API 2.0 (ECMA-402) | Standard |
| ECMAScript Internationalization API 4.0 (ECMA-402) | Draft |
| Proposals (with advanced stage and at least 1 implementation) | Draft |

