Javascript regex returns null

Question

I am trying to match this url:

https://play.spotify.com/user/randomuser/playlist/71ljVu3Ejccu2PzW6iXv0G

where random user and the ending id are changing.

I want to verify that the url is indeed a play.spotify.com link and matches that format.

I have this javascript function:

var verify = function(url){
    var re = new RegExp("(https:\/\/play.spotify.com\/user\/\w+?\/playlist\/\w+)", "g");
    var result = re.exec(url);
    console.log(result);
}

verify("https://play.spotify.com/user/useruser/playlist/71ljVu3Ejccu2PzW6iXv0G");

When I tested it out using a regex tester, it seems to work correctly:

enter image description here

The output of the console.log, however, is just null.

What am I doing wrong in the javascript? Why isn't the url properly matching?

You also might want to replace the domain name's .s into \.s. — Hauke P.
– Hauke P., Commented Jun 22, 2015 at 17:51

Bergi · Accepted Answer · 2015-06-22 17:58:02Z

5

"(https:\/\/play.spotify.com\/user\/\w+?\/playlist\/\w+)"

You're escaping the characters / and w here, which is not necessary in a string literal. Your string is equivalent to

"(https://play.spotify.com/user/w+?/playlist/w+)"

which obviously now is not the regex that you're looking for.

Don't use the RegExp constructor, use a regex literal:

var re = /(https:\/\/play.spotify.com\/user\/\w+?\/playlist\/\w+)/g;

If you really needed to use new RegExp for some reason, you'd have to escape the backslash character in your string: new RegExp("(https://play.spotify.com/user/\\w+?/playlist/\\w+)", "g").

edited Jun 22, 2015 at 17:58

answered Jun 22, 2015 at 17:51

Bergi

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1 Comment

WakeskaterX Over a year ago

In that last regex you forgot to escape the first \w+? as well.

Tom · Accepted Answer · 2015-06-22 17:53:03Z

1

You don't need to use the RegExp constructor, and can use the string.match(regex) function to get the result:

var verify = function(url) {
  var regex = /https:\/\/play.spotify.com\/user\/\w+?\/playlist\/\w+/g;
  var result = url.match(regex);
  console.log(result);
};

// Passes, logs the URL:
verify("https://play.spotify.com/user/useruser/playlist/71ljVu3Ejccu2PzW6iXv0G");

// Fails, logs null
verify("https://play.spotify.com/useruser/playlist/71ljVu3Ejccu2PzW6iXv0G");

See jsBin

answered Jun 22, 2015 at 17:53

Tom

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