Deprecated and obsolete features

This page lists features of JavaScript that are deprecated (that is, still available but planned for removal) and obsolete (that is, no longer usable).

Deprecated features

These deprecated features can still be used, but should be used with caution because they are expected to be removed entirely sometime in the future. You should work to remove their use from your code.

RegExp properties

The following properties are deprecated. This does not affect their use inreplacement strings:

Свойство	Описание
`$1-$9`	Parenthesized substring matches, if any.Warning: Using these properties can result in problems, since browser extensions can modify them. Avoid them!
`$_`	Смотрите`input`.
`$*`	Смотрите`multiline`.
`$&`	Смотрите`lastMatch`.
`$+`	Смотрите`lastParen`.
$`	Смотрите`leftContext`.
`$'`	Смотрите`rightContext`.
`input`	The string against which a regular expression is matched.
`lastMatch`	The last matched characters.
`lastParen`	The last parenthesized substring match, if any.
`leftContext`	The substring preceding the most recent match.
`rightContext`	The substring following the most recent match.

The following are now properties ofRegExp instances, no longer of theRegExp object:

Свойство	Описание
`global`	Whether or not to test the regular expression against all possible matches in a string, or only against the first.
`ignoreCase`	Whether or not to ignore case while attempting a match in a string.
`lastIndex`	The index at which to start the next match.
`multiline`	Whether or not to search in strings across multiple lines.
`source`	The text of the pattern.

RegExp methods

Thecompile() method is deprecated.
ThevalueOf method is no longer specialized forRegExp. UseObject.valueOf().

Function properties

Thecaller andarguments properties are deprecated, because they leak the function caller. Instead of the arguments property, you should use thearguments object inside function closures.

Legacy generator

Legacy generator function statement andLegacy generator function expression are deprecated. Usefunction* statement andfunction* expression instead.
JS1.7/JS1.8 Array comprehension andJS1.7/JS1.8 Generator comprehension are deprecated.

Iterator

StopIteration устарел.
Iterator устарел.

Object methods

watch andunwatch are deprecated. UseProxy instead.
__iterator__ устарел.
Object.prototype.__noSuchMethod__ is deprecated. UseProxy instead.

Методы даты

getYear иsetYear are affected by the Year-2000-Problem and have been subsumed bygetFullYear иsetFullYear.
You should usetoISOString instead of the deprecatedtoGMTString method in new code.
toLocaleFormat is deprecated.

Functions

Expression closures are deprecated. Use regularfunctions orarrow functions instead.

Proxy

Proxy.create andProxy.createFunction are deprecated. UseProxy instead.
The following traps are obsolete:
- hasOwn (Firefox bug 980565, Firefox 33).
- getEnumerablePropertyKeys (Firefox bug 783829, Firefox 37)
- getOwnPropertyNames (Firefox bug 1007334, Firefox 33)
- keys (Firefox bug 1007334, Firefox 33)

Escape sequences

Octal escape sequences (\ followed by one, two, or three octal digits) are deprecated in string and regular expression literals.
Theescape andunescape functions are deprecated. UseencodeURI,encodeURIComponent,decodeURI ordecodeURIComponent to encode and decode escape sequences for special characters.

Методы строк

HTML wrapper methods likeString.prototype.fontsize andString.prototype.big.
String.prototype.quote is removed from Firefox 37.
non standardflags parameter inString.prototype.search,String.prototype.match, andString.prototype.replace are deprecated.
String.prototype.substr probably won't be removed anytime soon, but it's defined inAnnex B of the ECMA-262 standard, whoseintroduction states: "… Programmers should not use or assume the existence of these features and behaviours when writing new ECMAScript code. …"

Obsolete features

These obsolete features have been entirely removed from JavaScript and can no longer be used as of the indicated version of JavaScript.

Объект

Свойство	Описание
`count`	Returns the number of enumerable properties directly on a user-defined object.
`parent`	Points to an object's context.
`Object.prototype.eval()`	Evaluates a string of JavaScript code in the context of the specified object.
`Object.observe()`	Asynchronously observing the changes to an object.
`Object.unobserve()`	Remove observers.
`Object.getNotifier()`	Creates an object that allows to synthetically trigger a change.