Table of contents
- 1. Deprecated features
- 1.1. RegExp properties
- 1.2. RegExp methods
- 1.3. Function properties
- 1.4. Date methods
- 1.5. Escape sequences
- 2. Obsolete features
This appendix 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:
| Property | Description |
|---|---|
$1, ..., $9 | Parenthesized substring matches, if any. |
$_ | See input. |
$* | See multiline. |
$& | See lastMatch. |
$+ | See lastParen. |
$` | See leftContext. |
$' | See 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:
| Property | Description |
|---|---|
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
The compile method is deprecated.
The valueOf method is no longer specialized for RegExp. Use Object.valueOf.
Function properties
The caller and arguments property are deprecated, because they leak the function caller. Instead of the arguments property, you should use the arguments object inside function closures.
Date methods
getYear and setYear are affected by the Year-2000-Problem and have been subsumed by getFullYear and setFullYear. Also you should use toISOString instead of the deprecated toGMTString method in new code.
Escape sequences
Octal escape sequences (\ followed by one, two, or three octal digits) are deprecated in string and regular expression literals.
The escape and unescape functions are deprecated. Use encodeURI, encodeURIComponent, decodeURI or decodeURIComponent to encode and decode escape sequences for special characters.
Obsolete features
These obsolete features have been entirely removed from JavaScript and can no longer be used as of the indicated version of JavaScript.
Objects
| Property | Description |
|---|---|
__count__ | Returns the number of enumerable properties directly on a user-defined object. |
| __parent__ | Points to an object's context. |
| Method | Description |
|---|---|
eval | Evaluates a string of JavaScript code in the context of the specified object. |
Functions
| Property | Description |
|---|---|
arity | Number of formal arguments. |
