Question

I am having a little trouble with regular expression.

I want to match a regular expression in a sentence.

Example :

John has two candy ::123::

and i am using this code to look for it:

var getid = x$('div').html().match(/::([^:]+)::/g);

To get the 123 our of the sentence.

So what’s my problem here?
I kept on getting an undefined value for getid var.

Answer 1

The problem is the g flag. You don’t use it with String#match. Remove it and it works fine (live copy | source):

var getid = x$('div').html().match(/::([^:]+)::/);
if (getid) {
    display("Found: " + getid[1]);
}
else {
    display("Not found");
}

If you want to find all of the matches in the text, use RegExp#exec and a loop (and the g flag) (live copy | source):

var rex = /::([^:]+)::/g;
var str = x$('div').html();
var getid;
while (getid = rex.exec(str)) {
    display("Found: " + getid[1]);
}

(For greater clarity, you might use

while ((getid = rex.exec(str)) != null) {

…since having an assignment in a test looks like a = instead of == typo; but it comes to the same thing other than readability.)

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Re your comment below asking about x$(this), it should make any difference. Here are the above examples reworked to use x$(this):

• One match: Example | source
• Loop: Example | source