RegExp.html
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<pre class="prettyprint lang-js"><span id='RegExp'>/**
</span> * @class RegExp
*
* Creates a regular expression object for matching text according to a pattern.
*
* When using the constructor function, the normal string escape rules (preceding
* special characters with \ when included in a string) are necessary. For
* example, the following are equivalent:
*
* var re = new RegExp("\\w+");
* var re = /\w+/;
*
* Notice that the parameters to the literal format do not use quotation marks to
* indicate strings, while the parameters to the constructor function do use
* quotation marks. So the following expressions create the same regular
* expression:
*
* /ab+c/i;
* new RegExp("ab+c", "i");
*
* # Special characters in regular expressions
*
* | Character | Meaning
* |:-----------------|:--------------------------------------------------------------------------------------
* | `\` | For characters that are usually treated literally, indicates that the next character
* | | is special and not to be interpreted literally.
* | | For example, `/b/` matches the character 'b'. By placing a backslash in front of b, that
* | | is by using `/\b/`, the character becomes special to mean match a word boundary.
* | |
* | | _or_
* | |
* | | For characters that are usually treated specially, indicates that the next character is
* | | not special and should be interpreted literally.
* | |
* | | For example, `*` is a special character that means 0 or more occurrences of the preceding
* | | character should be matched; for example, `/a*\/` means match 0 or more "a"s. To match *
* | | literally, precede it with a backslash; for example, `/a\*\/` matches 'a*'.
* | |
* | `^` | Matches beginning of input. If the multiline flag is set to true, also matches
* | | immediately after a line break character.
* | |
* | | For example, `/^A/` does not match the 'A' in "an A", but does match the first 'A' in
* | | "An A".
* | |
* | `$` | Matches end of input. If the multiline flag is set to true, also matches immediately
* | | before a line break character.
* | |
* | | For example, `/t$/` does not match the 't' in "eater", but does match it in "eat".
* | |
* | `*` | Matches the preceding item 0 or more times.
* | |
* | | For example, `/bo*\/` matches 'boooo' in "A ghost booooed" and 'b' in "A bird warbled",
* | | but nothing in "A goat grunted".
* | |
* | `+` | Matches the preceding item 1 or more times. Equivalent to `{1,}`.
* | |
* | | For example, `/a+/` matches the 'a' in "candy" and all the a's in "caaaaaaandy".
* | |
* | `?` | Matches the preceding item 0 or 1 time.
* | |
* | | For example, `/e?le?/` matches the 'el' in "angel" and the 'le' in "angle."
* | |
* | | If used immediately after any of the quantifiers `*`, `+`, `?`, or `{}`, makes the quantifier
* | | non-greedy (matching the minimum number of times), as opposed to the default, which is
* | | greedy (matching the maximum number of times).
* | |
* | | Also used in lookahead assertions, described under `(?=)`, `(?!)`, and `(?:)` in this table.
* | |
* | `.` | (The decimal point) matches any single character except the newline characters: \n \r
* | | \u2028 or \u2029. (`[\s\S]` can be used to match any character including new lines.)
* | |
* | | For example, `/.n/` matches 'an' and 'on' in "nay, an apple is on the tree", but not 'nay'.
* | |
* | `(x)` | Matches `x` and remembers the match. These are called capturing parentheses.
* | |
* | | For example, `/(foo)/` matches and remembers 'foo' in "foo bar." The matched substring can
* | | be recalled from the resulting array's elements `[1], ..., [n]` or from the predefined RegExp
* | | object's properties `$1, ..., $9`.
* | |
* | `(?:x)` | Matches `x` but does not remember the match. These are called non-capturing parentheses.
* | | The matched substring can not be recalled from the resulting array's elements `[1], ..., [n]`
* | | or from the predefined RegExp object's properties `$1, ..., $9`.
* | |
* | `x(?=y)` | Matches `x` only if `x` is followed by `y`. For example, `/Jack(?=Sprat)/` matches 'Jack' only if
* | | it is followed by 'Sprat'. `/Jack(?=Sprat|Frost)/` matches 'Jack' only if it is followed by
* | | 'Sprat' or 'Frost'. However, neither 'Sprat' nor 'Frost' is part of the match results.
* | |
* | `x(?!y)` | Matches `x` only if `x` is not followed by `y`. For example, `/\d+(?!\.)/` matches a number only
* | | if it is not followed by a decimal point.
* | |
* | | `/\d+(?!\.)/.exec("3.141")` matches 141 but not 3.141.
* | |
* | `x|y` | Matches either `x` or `y`.
* | |
* | | For example, `/green|red/` matches 'green' in "green apple" and 'red' in "red apple."
* | |
* | `{n}` | Where `n` is a positive integer. Matches exactly n occurrences of the preceding item.
* | |
* | | For example, `/a{2}/` doesn't match the 'a' in "candy," but it matches all of the a's
* | | in "caandy," and the first two a's in "caaandy."
* | |
* | `{n,}` | Where `n` is a positive integer. Matches at least n occurrences of the preceding item.
* | |
* | | For example, `/a{2,}/` doesn't match the 'a' in "candy", but matches all of the a's in
* | | "caandy" and in "caaaaaaandy."
* | |
* | `{n,m}` | Where `n` and `m` are positive integers. Matches at least `n` and at most `m` occurrences of the
* | | preceding item.
* | |
* | | For example, `/a{1,3}/` matches nothing in "cndy", the 'a' in "candy," the first two a's
* | | in "caandy," and the first three a's in "caaaaaaandy". Notice that when matching
* | | "caaaaaaandy", the match is "aaa", even though the original string had more a's in it.
* | |
* | `[xyz]` | A character set. Matches any one of the enclosed characters. You can specify a range of
* | | characters by using a hyphen.
* | |
* | | For example, `[abcd]` is the same as `[a-d]`. They match the 'b' in "brisket" and the 'c'
* | | in "chop".
* | |
* | `[^xyz]` | A negated or complemented character set. That is, it matches anything that is not
* | | enclosed in the brackets. You can specify a range of characters by using a hyphen.
* | |
* | | For example, `[^abc]` is the same as `[^a-c]`. They initially match 'r' in "brisket" and
* | | 'h' in "chop."
* | |
* | `[\b]` | Matches a backspace. (Not to be confused with `\b`.)
* | |
* | `\b` | Matches a word boundary, such as a space. (Not to be confused with `[\b]`.)
* | |
* | | For example, `/\bn\w/` matches the 'no' in "noonday"; `/\wy\b/` matches the 'ly' in
* | | "possibly yesterday."
* | |
* | `\B` | Matches a non-word boundary.
* | |
* | | For example, `/\w\Bn/` matches 'on' in "noonday", and `/y\B\w/` matches 'ye' in "possibly
* | | yesterday."
* | |
* | `\cX` | Where X is a letter from A - Z. Matches a control character in a string.
* | |
* | | For example, `/\cM/` matches control-M in a string.
* | |
* | `\d` | Matches a digit character in the basic Latin alphabet. Equivalent to `[0-9]`.
* | |
* | | For example, `/\d/` or `/[0-9]/` matches '2' in "B2 is the suite number."
* | |
* | `\D` | Matches any non-digit character in the basic Latin alphabet. Equivalent to `[^0-9]`.
* | |
* | | For example, `/\D/` or `/[^0-9]/` matches 'B' in "B2 is the suite number.
* | |
* | `\f` | Matches a form-feed.
* | |
* | `\n` | Matches a linefeed.
* | |
* | `\r` | Matches a carriage return.
* | |
* | `\s` | Matches a single white space character, including space, tab, form feed, line feed and
* | | other unicode spaces. Equivalent to:
* | |
* | | `[\t\n\v\f\r \u00a0\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u200b\u2028\u2029\u3000]`
* | |
* | | For example, `/\s\w*\/` matches ' bar' in "foo bar."
* | |
* | `\S` | Matches a single character other than white space. Equivalent to:
* | |
* | | `[^\t\n\v\f\r \u00a0\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u200b\u2028\u2029\u3000]`
* | |
* | | For example, `/\S\w*\/` matches 'foo' in "foo bar."
* | |
* | `\t` | Matches a tab.
* | |
* | `\v` | Matches a vertical tab.
* | |
* | `\w` | Matches any alphanumeric character from the basic Latin alphabet, including the
* | | underscore. Equivalent to `[A-Za-z0-9_]`.
* | |
* | | For example, `/\w/` matches 'a' in "apple," '5' in "$5.28," and '3' in "3D."
* | |
* | `\W` | Matches any character that is not a word character from the basic Latin alphabet. Equivalent
* | | to `[^A-Za-z0-9_]`.
* | |
* | | For example, `/\W/` or `/[^A-Za-z0-9_]/` matches '%' in "50%."
* | |
* | `\n` | Where `n` is a positive integer. A back reference to the last substring matching the n
* | | parenthetical in the regular expression (counting left parentheses).
* | |
* | | For example, `/apple(,)\sorange\1/` matches 'apple, orange,' in "apple, orange, cherry,
* | | peach." A more complete example follows this table.
* | |
* | `\0` | Matches a NULL character. Do not follow this with another digit.
* | |
* | `\xhh` | Matches the character with the code `hh` (two hexadecimal digits)
* | |
* | `\uhhhh` | Matches the character with the Unicode value `hhhh` (four hexadecimal digits)
*
* The literal notation provides compilation of the regular expression when the expression is evaluated. Use
* literal notation when the regular expression will remain constant. For example, if you use literal notation
* to construct a regular expression used in a loop, the regular expression won't be recompiled on each iteration.
*
* The constructor of the regular expression object, for example, new RegExp("ab+c"), provides runtime
* compilation of the regular expression. Use the constructor function when you know the regular expression
* pattern will be changing, or you don't know the pattern and are getting it from another source, such as user input.
*
* <div class="notice">
* Documentation for this class comes from <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/RegExp">MDN</a>
* and is available under <a href="http://creativecommons.org/licenses/by-sa/2.0/">Creative Commons: Attribution-Sharealike license</a>.
* </div>
*/
<span id='RegExp-method-constructor'>/**
</span> * @method constructor
* Creates new regular expression object.
*
* @param {String} pattern
* The text of the regular expression.
* @param {String} flags
* If specified, flags can have any combination of the following values:
*
* - "g" - global match
* - "i" - ignore case
* - "m" - Treat beginning and end characters (^ and $) as working over multiple lines
* (i.e., match the beginning or end of _each_ line (delimited by \n or \r), not
* only the very beginning or end of the whole input string)
*/
//Methods
<span id='RegExp-method-exec'>/**
</span> * @method exec
* Executes a search for a match in its string parameter.
*
* If the match succeeds, the `exec` method returns an array and updates properties of the regular
* expression object. The returned array has the matched text as the first item, and then one item for
* each capturing parenthesis that matched containing the text that was captured. If the match fails,
* the `exec` method returns `null`.
*
* If you are executing a match simply to find true or false, use the `test` method or the `String
* search` method.
*
* Consider the following example:
*
* // Match one d followed by one or more b's followed by one d
* // Remember matched b's and the following d
* // Ignore case
* var re = /d(b+)(d)/ig;
* var result = re.exec("cdbBdbsbz");
*
* The following table shows the results for this script:
*
* | Object | Property/Index | Description | Example
* |:-----------------|:---------------|:---------------------------------------------------------------------|:---------------------
* | `result` | | The content of myArray. | `["dbBd", "bB", "d"]`
* | | `index` | The 0-based index of the match in the string | `1`
* | | `input` | The original string. | `cdbDdbsbz`
* | | `[0]` | The last matched characters. | `dbBd`
* | | `[1], ...[n]` | The parenthesized substring matches, if any. The number of possible | `[1] = bB`
* | | | parenthesized substrings is unlimited. | `[2] = d`
* | `re` | `lastIndex` | The index at which to start the next match. | `5`
* | | `ignoreCase` | Indicates the "`i`" flag was used to ignore case. | `true`
* | | `global` | Indicates the "`g`" flag was used for a global match. | `true`
* | | `multiline` | Indicates the "`m`" flag was used to search in strings across | `false`
* | | | multiple lines. |
* | | `source` | The text of the pattern. | d(b+)(d)
*
* If your regular expression uses the "`g`" flag, you can use the `exec` method multiple times to find
* successive matches in the same string. When you do so, the search starts at the substring of `str`
* specified by the regular expression's `lastIndex` property (`test` will also advance the `lastIndex`
* property). For example, assume you have this script:
*
* var myRe = /ab*\/g;
* var str = "abbcdefabh";
* var myArray;
* while ((myArray = myRe.exec(str)) != null)
* {
* var msg = "Found " + myArray[0] + ". ";
* msg += "Next match starts at " + myRe.lastIndex;
* print(msg);
* }
*
* This script displays the following text:
*
* Found abb. Next match starts at 3
* Found ab. Next match starts at 9
*
* You can also use `exec()` without creating a RegExp object:
*
* var matches = /(hello \S+)/.exec('This is a hello world!');
* alert(matches[1]);
*
* This will display an alert containing 'hello world!';
*
* @param {String} str The string against which to match the regular expression.
* @return {Array} Array of results or `NULL`.
*/
<span id='RegExp-method-test'>/**
</span> * @method test
* Tests for a match in its string parameter.
*
* When you want to know whether a pattern is found in a string use the test method (similar to the
* `String.search` method); for more information (but slower execution) use the exec method (similar to
* the `String.match` method). As with exec (or in combination with it), test called multiple times on
* the same global regular expression instance will advance past the previous match.
*
* The following example prints a message which depends on the success of the test:
*
* function testinput(re, str){
* if (re.test(str))
* midstring = " contains ";
* else
* midstring = " does not contain ";
* document.write (str + midstring + re.source);
* }
*
* @param {String} str The string against which to match the regular expression.
* @return {Boolean} true if string contains any matches, otherwise returns false.
*/
<span id='RegExp-method-toString'>/**
</span> * @method toString
* Returns a string representing the specified object. Overrides the `Object.prototype.toString`
* method.
*
* The RegExp object overrides the `toString` method of the `Object` object; it does not inherit
* `Object.toString`. For RegExp objects, the `toString` method returns a string representation of the
* regular expression.
*
* The following example displays the string value of a RegExp object:
*
* myExp = new RegExp("a+b+c");
* alert(myExp.toString()); // displays "/a+b+c/"
*
* @return {String} Regular expression as a string.
*/
//Properties
// Note that several of the RegExp properties have both long and short (Perl-like) names.
// Both names always refer to the same value. Perl is the programming language from which
// JavaScript modeled its regular expressions.
<span id='RegExp-property-global'>/**
</span> * @property {Boolean} global
* Whether to test the regular expression against all possible matches in a
* string, or only against the first.
*
* `global` is a property of an individual regular expression object.
*
* The value of `global` is true if the "`g`" flag was used; otherwise, `false`. The "`g`" flag
* indicates that the regular expression should be tested against all possible matches in a string.
*
* You cannot change this property directly.
*/
<span id='RegExp-property-ignoreCase'>/**
</span> * @property {Boolean} ignoreCase
* Whether to ignore case while attempting a match in a string.
*
* `ignoreCase` is a property of an individual regular expression object.
*
* The value of `ignoreCase` is true if the "`i`" flag was used; otherwise, false. The "`i`" flag indicates
* that case should be ignored while attempting a match in a string.
*
* You cannot change this property directly.
*/
<span id='RegExp-property-lastIndex'>/**
</span> * @property {Number} lastIndex
* The index at which to start the next match. A read/write integer property that specifies the index
* at which to start the next match.
*
* `lastIndex` is a property of an individual regular expression object.
*
* This property is set only if the regular expression used the "`g`" flag to indicate a global search.
* The following rules apply:
*
* - If `lastIndex` is greater than the length of the string, `regexp.test` and `regexp.exec` fail,
* and `lastIndex` is set to 0.
* - If `lastIndex` is equal to the length of the string and if the regular expression matches the
* empty string, then the regular expression matches input starting at `lastIndex`.
* - If `lastIndex` is equal to the length of the string and if the regular expression does not match
* the empty string, then the regular expression mismatches input, and `lastIndex` is reset to 0.
* - Otherwise, `lastIndex` is set to the next position following the most recent match.
*
* For example, consider the following sequence of statements:
*
* - `re = /(hi)?/g` Matches the empty string.
* - `re("hi")` Returns `["hi", "hi"]` with `lastIndex` equal to 2.
* - `re("hi")` Returns `[""]`, an empty array whose zeroth element is the match string. In this
* case, the empty string because `lastIndex` was 2 (and still is 2) and "`hi`" has length 2.
*/
<span id='RegExp-property-multiline'>/**
</span> * @property {Boolean} multiline
* Whether or not to search in strings across multiple lines.
*
* `multiline` is a property of an individual regular expression object..
*
* The value of `multiline` is true if the "`m`" flag was used; otherwise, `false`. The "`m`" flag
* indicates that a multiline input string should be treated as multiple lines. For example, if "`m`"
* is used, "`^`" and "`$`" change from matching at only the start or end of the entire string to the
* start or end of any line within the string.
*
* You cannot change this property directly.
*/
<span id='RegExp-property-source'>/**
</span> * @property {String} source
* The text of the pattern.
*
* A read-only property that contains the text of the pattern, excluding the forward slashes.
*
* `source` is a property of an individual regular expression object.
*
* You cannot change this property directly.
*/</pre>
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