JavaScript preg_quote

Quote regular expression characters plus an optional character

function preg_quote (str, delimiter) {
    // Quote regular expression characters plus an optional character  
    // 
    // version: 1109.2015
    // discuss at: http://phpjs.org/functions/preg_quote    // +   original by: booeyOH
    // +   improved by: Ates Goral (http://magnetiq.com)
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Onno Marsman
    // +   improved by: Brett Zamir (http://brett-zamir.me)    // *     example 1: preg_quote("$40");
    // *     returns 1: '\$40'
    // *     example 2: preg_quote("*RRRING* Hello?");
    // *     returns 2: '\*RRRING\* Hello\?'
    // *     example 3: preg_quote("\\.+*?[^]$(){}=!<>|:");    // *     returns 3: '\\\.\+\*\?\[\^\]\$\(\)\{\}\=\!\<\>\|\:'
    return (str + '').replace(new RegExp('[.\\\\+*?\\[\\^\\]$(){}=!<>|:\\' + (delimiter || '') + '-]', 'g'), '\\$&');
}

external links: original PHP docs | raw js source

Examples

» Example 1

Running

1	preg_quote("$40");

Should return

'\$40'

» Example 2

Running

1	preg_quote("RRRING Hello?");

Should return

1	'\RRRING\ Hello\?'

Dependencies

No dependencies, you can use this function standalone.

Open syntax issues

php.js uses JsLint to help us keep our code consistent and prevent some common bugs.

Eventually we want all code to pass or at least take into consideration most fixes suggested by JsLint, following this JsLint configuration we’ve decided on.

Authors

Thanks to the following developers, you get to have preg_quote goodness in JavaScript.

booeyOH ( original )
Ates Goral ( improved )
Kevin van Zonneveld ( improved )
Brett Zamir ( improved )
Onno Marsman ( bugfixed )

Comments

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Use:

[CODE]
your_stuff('here');
[/CODE]

for proper code formatting
By submitting code here you are allowing us to use it in php.js hence dual licensing it under the MIT and GPL licenses

Brett Zamir
20 Jul '11

In addition to my post just now, there is also the possibility of ECMAScript itself supporting the more advanced syntax (not sure if they would for reasons of backward-compatibility).

Brett Zamir
20 Jul '11

@Jon. L: Yes, that's true--I guess you are talking about the fact that we escape "<" and ">"? Yeah, those could be removed, but 1) It is harmless to escape them, 2) Safer to behave like PHP in case someone is passing something back to PHP, 3) I'm hoping at some point for us to port and build upon XRegExp so that our library does support the full PCRE syntax.

Jon L.
15 Jul '11

PHP regex (PCRE) and JS regex (ECMA) are not 100% compatible:
http://www.regular-expressions.info/refflavors.html << see chart for differences.

Kevin van Zonneveld
13 Apr '08

@ ?: Hi, thanks for the contribution. There are some things that keep me from including this in php.js. Firstly I don't know your name so I cannot credit you, Secondly, I don't know if the perl regular expressions are 100% compatible with the javascript regex engine. Do you know this?

Simple preg_replace_callback
12 Apr '08

[CODE="Javascript"]
function preg_replace_callback(reg, cbck, str){
return str.replace(REGEXP, function(arguments){return window[cbck](arguments);});
}
[/CODE]

Kevin van Zonneveld
23 Jan '08

@ Ates Goral: Kaizen principles FTW

Ates Goral
23 Jan '08

After looking at the implementation of addslashes(), I realized that this could have been simply achieved with:

[CODE="Javascript"]
return str.replace(/([\\\.\+\*\?\[\^\]\$\{\}\=\!\<\>\|\:])/g, "\\$1");
[/CODE]

I don't know why I chose to use a replacement function in the first place :)

Kevin van Zonneveld
23 Jan '08

@ Ates Goral: There you go, 2 gold medals :)

Ates Goral
23 Jan '08

Here's my take:

[CODE="Javascript"]
function preg_quote(str) {
// * example 1: preg_quote("*RRRING* Hello?");
// * returns 1: "\\*RRRING\\* Hello\\?"
// * example 2: preg_quote("\\.+*?[^]$(){}=!<>|:");
// * returns 2: "\\\\\\.\\+\\*\\?\\[\\^\\]\\$\$\$\\{\\}\\=\\!\\<\\>\\|\\:"

return str.replace(/[\\\.\+\*\?\[\^\]\$\{\}\=\!\<\>\|\:]/g, function(c) { return "\\" + c; });
}
[/CODE]

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