Javascript array string to regex literal

Question

I have a working example here: http://jsfiddle.net/R7KuK/

I've tried to create an array containing full regular expressions with regex delimiters and set flags, but the RegExp object parses given strings as strings, not as regular expressions.

  var regex = "/wolves/i"

vs.

  var regex = /wolves/i

My question is: How do I convert string-ed regex into an actual regular expression?

UPDATE: It wasn't until Felix King kindly explained to me that

var array = ["/wolves/i", "/Duck/"];

can safely become:

var array = [/wolves/i, /Duck/];

Check stackoverflow.com/questions/4589587/… and stackoverflow.com/questions/874709/… — arunes
– arunes, Commented Mar 7, 2012 at 20:53
Why don't you create the array as [/wolves/i, /Duck/]? Why do you use strings at all? That seems to be an unnecessary complication to me. — Felix Kling
– Felix Kling, Commented Mar 7, 2012 at 20:55
@FelixKling: I wasn't aware that was even possible, not to use the quotes. — User2121315
– User2121315, Commented Mar 7, 2012 at 20:57
How did you create regular expressions then? /.../ denotes a regex literal. You must have been using /.../.test(...) or str.match(/.../) before. Anyways, here is some documentation: developer.mozilla.org/en/JavaScript/Guide/Regular_Expressions — Felix Kling
– Felix Kling, Commented Mar 7, 2012 at 20:58
@FelixKling: Yes, I've been using str.match(/.../), though I wasn't aware it was possible not to use strings in arrays, assuming regexp's could contain unescaped characters and fail; or I could be trying to match for a dot and accidentally close one array item. — User2121315
– User2121315, Commented Mar 7, 2012 at 21:02

kitti · Accepted Answer · 2012-03-07 20:53:17Z

3

Try this:

var regexSplit = regex.split( '/' );
var realRegex = new RegExp( regexSplit[1], regexSplit[2] );

Or better:

var regexMatch = regex.match( /^\/(.*)\/([^\/]*)$/ );
var realRegex = new RegExp( regexMatch[1], regexMatch[2] );

Better cause if your regex contains '/', the first one will fail. ;)

answered Mar 7, 2012 at 20:53

kitti

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Community · Accepted Answer · 2017-05-23 12:21:12Z

0

as stolen from here:

Use the RegExp object constructor to create a regular expression from a string:
var re = new RegExp("a|b", "i");
// same as
var re = /a|b/i;

edited May 23, 2017 at 12:21

CommunityBot

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answered Mar 7, 2012 at 20:54

Scott Weaver

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1 Comment

Felix Kling Over a year ago

If you copy another answer verbatim, shouldn't this question be closed as a duplicate then?

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