jquery isolate class with variable name via regular expressions

Question

Please note that I don't know what the full class I'm wanting to isolate is, only its format, which is for example:

class="loadable context-enc encounterTimelineEncounterDateitem"

What I'm looking for is context-enc or something that matches:

.match(/\bcontext-[a-z]+\b/)

and it's really the [a-z]+ part that I want to discover. I don't want to so much test whether there IS a class in there that matches, but want to know what the string after "context-" is (in this case 'enc'). Something like:

function getcontext(class, 'context-'){ .. }

Nathan Taylor · Accepted Answer · 2014-09-15 22:49:30Z

2

You can wrap the [a-z+] in your regex in parentheses to get the value back in a capture group:

"context-enc".match(/\bcontext-([a-z]+)\b/)

["context-enc", "enc"]

answered Sep 15, 2014 at 22:49

Nathan Taylor

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1 Comment

Samuel Fullman Over a year ago

THANKS! I was torn between voting yours or @Ben_Thielker as the accepted answer - you both answered a part of the question, and now I know how to approach back-references in JS (which I already knew in PHP's preg_match() using the 3rd parameter.

Ben Thielker · Accepted Answer · 2014-09-15 23:27:11Z

0

The following function would likely return what you want...

function getContext(className, withString){
    var r = new RegExp("\\b"+ withString +"[a-z]+\\b");
    var s = new RegExp("^"+withString);
    return className.match(r)[0].replace(s,'');
}

If you build the regular expression dynamically you can insert your variable content into it, and then to isolate the [a-z]+ portion just remove the searched for string from the result.

EDIT: Using @nathan-taylor's capture group suggestion we can simplify the function to:

function getContext(className, withString){
    var r = new RegExp("\\b"+ withString +"([a-z]+)\\b");
    return className.match(r)[1];
}

edited Sep 15, 2014 at 23:27

answered Sep 15, 2014 at 23:04

Ben Thielker

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