Question

I need to build a string from the data contained in this url using javascript/jQuery:

http://www.example.com/members/admin/projects/?projectid=41

The string returned should look as follows:

/ajax/projects.php?projectid=41

Obviously if there is no query string present, the method should still return a string of the same format minus the query string. e.g.

http://www.example.com/members/admin/messages/

should return…

/ajax/messages.php

I’ve made numerous attempts, all met without success due to my poor grasp of regular expressions, and it feels as though the ore I rad on the subject the more I am confusing myself.

If someone could help it would be greatly appreciated.

EDIT: The ‘admin’ portion of the url is a users ‘username’ and could be anything.

Answer 1

Here’s a function that will take your URL and return a new one according to the rules you’ve listed above:

function processURL(url) {
    var base = "", query = "";
    var matches = url.match(/([^\/\?]+)(\/$|$|\?|\/\?)/);
    if (matches) {
        base = matches[1];
        matches = url.match(/\?[^\?]+$/);
        if (matches) {
            query = matches[0];
        }
    }
    return("/ajax/" + base + ".php" + query);
}

And, a test app that shows it working on a bunch of URLs: http://jsfiddle.net/jfriend00/UbDfn/

Input URLs:

var urls = [
    "http://www.example.com/members/admin/projects/?projectid=41",
    "http://www.example.com/members/bob/messages/",
    "http://www.example.com/members/jill/projects/",
    "http://www.example.com/members/alice/projects?testid=99",
    "http://www.example.com/members/admin/projects/?testid=99"
];

Output results:

/ajax/projects.php?projectid=41
/ajax/messages.php
/ajax/projects.php
/ajax/projects.php?testid=99
/ajax/projects.php?testid=99

To explain, the first regular expression looks for:

a slash
followed by one or more characters that is not a slash and not a question mark
followed by one of the four sequences
    /$    a slash at the end of the string
    $     end of the string
    ?     a question mark
    /?    a slash followed by a question mark

The point of this regex is to get the last segment of the path that comes before either the end of the string or the query parameters and it’s tolerant of whether the last trailing slash is there or not and whether there are any query parameters.