JavaScript Regular Expression Can't get a matched group

Question

I'm trying to use JavaScript regular expression with the exec function and hoping to get matches for a group. I just can't figure out why I'm getting no matches.

Here is my code:

var elementClass="validate[required]"
var myRegexp = /validate\\[(*)\\]/g;
var match = myRegexp.exec(elementClass);

match is null every time. I can't figure out why. It should be getting "required".

Thanks for the help!

Java != JavaScript. I changed the title to reflect that.

JayC
– JayC

2013-03-03 00:13:50 +00:00
Commented Mar 3, 2013 at 0:13 — JayC
– JayC, Commented Mar 3, 2013 at 0:13

Niet the Dark Absol · Accepted Answer · 2013-03-03 00:06:37Z

3

Use this instead:

var myRegexp = /validate\[(.*)\]/;

First of all you only need one backslash to escape - otherwise you're searching for a literal backslash followed by the special meaning of what you were trying to escape.

Second, * just means "zero or more of the last thing", which in this case makes no sense because there is nothing there. . means "anything" (well, almost) so .* means "any number of anythings".

Finally, the g flag is unnecessary here, especially if you're trying to capture a part of the result.

answered Mar 3, 2013 at 0:06

Niet the Dark Absol

326k86 gold badges480 silver badges604 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

user1513171 Over a year ago

Ok that works but one thing I'm noticing is I keep getting 2 results. So match has 2 elements. The first element is always just exactly what was put in, and the second is the part between the brackets, in this case required.

Niet the Dark Absol Over a year ago

That's how regexes work. The first element of the match array is always the full match, then each subsequent entry corresponds to the next subpattern (in this case, the disabled string)

Niet the Dark Absol · Accepted Answer · 2013-03-03 00:30:16Z

2

1) You have to many slashes

var myRegexp = /validate\[(.*?)\]/g;

2) If you want to match the part in square brackets only, you should use groups

var result = match[1];

edited Mar 3, 2013 at 0:30

Niet the Dark Absol

326k86 gold badges480 silver badges604 bronze badges

answered Mar 3, 2013 at 0:06

VladL

13.1k10 gold badges69 silver badges85 bronze badges

7 Comments

Niet the Dark Absol Over a year ago

Doesn't anyone bother testing their code before using it in an answer?

VladL Over a year ago

@Kolink can't check it right now, but don't see any reason for why it's null

Niet the Dark Absol Over a year ago

Just hit F12, instant JavaScript console. See my answer for why yours won't work.

VladL Over a year ago

@Kolink for some reason either my nor your regex are working, should I downvote your too? gyazo.com/baeb57eb55676f6257222de3f83ef036

Niet the Dark Absol Over a year ago

You are indeed correct. My apologies. I've become so accustomed to using String.match rather than RegExp.exec that I had forgotten how g works differently in the latter case. Downvote removed, upvote added.

|

Collectives™ on Stack Overflow

JavaScript Regular Expression Can't get a matched group

2 Answers 2

2 Comments

7 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

7 Comments

Your Answer

Sign up or log in

Post as a guest

Related