find a string with regex and javascript

Question

I am trying to match the string 6c81748b9239e96e it's random each time. Using the following code below. My problem is that it matches the entire string and I only need the random string that contains the letters and numbers.

String

<a href="playgame.aspx?gid=4&tag=6c81748b9239e96e">Play</a>

javascript regex

string.match(/\&tag\=[A-Za-z0-9]+\"\>/i);

What else than letters and numbers do you have in your string? — Hauns TM, Jun 06 '12 at 10:18
@Hauns TM i'm not understanding what you are asking? I added the full string — Daniel, Jun 06 '12 at 10:20
The unedited question didn't show all the needed information! — Hauns TM, Jun 06 '12 at 10:21
@HaunsTM that's why it was edited :-) I didn't add anything actually, it was there, but hidden by SO's xss defense. — Florian Margaine, Jun 06 '12 at 10:26

score 1 · Answer 1 · edited May 23 '17 at 12:03

1

You could use Regular Expression Groups to match, and later access the pattern you are after. The regex you will need to use is like so: /\&tag\=([A-Za-z0-9]+)\"\>/i. The round brackets (( and )) will denote the group you want to capture. You can then access the capture group as shown here.

EDIT: Upon closer inspection it seems that you might be using an incorrect regular expression. I am not really used to Javascript regexes but it seems that you are escaping the & and = and>, which is not required. Try this instead: /&tag=([A-Za-z0-9]+)\">/i.

edited May 23 '17 at 12:03

Community

1
1

answered Jun 06 '12 at 10:21

npinti

51,780
5
72
96

@Mr.1.0: I think that you are using a wrong regular expression. I have tested a new one which seems to work. Please check my updated response. – npinti Jun 06 '12 at 10:27

score 1 · Accepted Answer · edited May 23 '17 at 11:55

Here is my suggestion:

Add the snippet provided by @Artem Barger to your code: https://stackoverflow.com/a/901144/851498 You need to slightly modify it, though (adding the str argument):

function getParameterByName( name, str )
{
    name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
    var regexS = "[\\?&]" + name + "=([^&#]*)";
    var regex = new RegExp(regexS);
    var results = regex.exec( str );
    if(results == null)
        return "";
    else
      return decodeURIComponent(results[1].replace(/\+/g, " "));
}

Use it this way:

var str = getParameterByName( 'tag', string );

Jsfiddle demo: http://jsfiddle.net/Ralt/u9MAv/

score 0 · Answer 3 · answered Jun 06 '12 at 10:25

0

var myregexp = /(&tag=)([A-Za-z0-9]+)\b/img;
var match = myregexp.exec(subject);
while (match != null) {
    for (var i = 0; i < match.length; i++) {
        // matched text: match[i]
    }
    match = myregexp.exec(subject);
}

answered Jun 06 '12 at 10:25

Cylian

10,970
4
42
55

score 0 · Answer 4 · answered Jun 06 '12 at 10:29

Your regex

&tag=([A-Za-z\d]+)"

It's simplified (you escaped too much) and parenthesis were added to put the thing you want in group 1

In javascript this becomes

var myregexp = /&tag=([A-Za-z\d]+)"/;
var match = myregexp.exec(subject);
if (match != null) {
    result = match[1];
} else {
    result = "";
}

Explanation

Match the characters “&tag=” literally «&tag=»
Match the regular expression below and capture its match into backreference number 1 «([A-Za-z\d]+)»
   Match a single character present in the list below «[A-Za-z\d]+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
      A character in the range between “A” and “Z” «A-Z»
      A character in the range between “a” and “z” «a-z»
      A single digit 0..9 «\d»
Match the character “"” literally «"»

find a string with regex and javascript

4 Answers4