Question

I’m attempting to do a find and replace using regular expressions and grabbing the first (and only in this case) backreference as a variable.

var RegexSearchString = "/((?:^(?:https?://|www\\d{0,3}[.])(?:.*?/)|(?:[a-z0-9.\\-]+[.][a-z]{2,4}/))(?:.*?/))/";
var test = "http://foo.bar.net/interestingbit/lots/of/other/stuff/here";
alert(test);
test.replace(umassURLRegexSearchString, "$1");
alert(test);

The expected result should be an alert with:
http://foo.bar.net/interestingbit/lots/of/other/stuff/here

followed by an alert with:
http://foo.bar.net/interestingbit/

Both alerts contain the value of the test variable as first initialized. Any ideas as to where this is breaking down?

Answer 1

You need to:

1. Add a new capture group to separate the first folder on the path from the rest
2. move the end parenthesis in your regex to before the new capture group
3. Assign the result of the regex back to test
4. Escape all of the / characters in your regex

The code with all of these changes is:

var RegexSearchString = /^((?:(?:https?:\/\/|www\d{0,3}[.])(?:.*?\/)|(?:[a-z0-9.\-]+[.][a-z]{2,4}\/))(?:.*?\/))(?:.*?\/)*/;
var test = "http://foo.bar.net/interestingbit/lots/of/other/stuff/here/";
alert(test);
test = test.replace(RegexSearchString, "$1");
alert(test);

Check it out here: http://jsfiddle.net/jheHR/1/