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 in replacement 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 of RegExp instances, no longer of the RegExp 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

Function properties

  • The caller and arguments properties are deprecated, because they leak the function caller. Instead of the arguments property, you should use the arguments object inside function closures.

Legacy generator


Object methods

  • watch and unwatch are deprecated. Use Proxy instead.
  • __iterator__ устарел.
  • Object.prototype.__noSuchMethod__ is deprecated. Use Proxy instead.

Методы даты



Escape sequences

Методы строк

Obsolete features

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


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.


Свойство Описание
arity Number of formal arguments.


Свойство Описание
Array.observe() Асинхронный просмотр изменений в массивах.
Array.unobserve() Remove observers.





Смотрите E4X.

Sharp variables