The Endpoint Resolver is a simple library that takes a URL and returns the final destination of that URL. It tries to follow a Location: header.

How it works

Given the URL, it gets passes to a server side resolver that hits the URL to get the headers. If a Location: header appears it is a redirect (ignoring 301, 302 for now, so a 200 + Location would count).

Since this happens via JSONP, it happens asynchronously via appending the script to the DOM. This is why you pass in a callback that will be passed the new URL, and the original one.

If the URL has been changed they will of course be different, and a simple helper Endpoint.isRedirecting(url, orig) will do that test for you.

Why?

The reason I built this was for a Twitter client. Seeing tinyurl / snurl / is.gd / twurl / .... URLs is ugly, and it can be scary not knowing where you are going, so wouldn't it be nice to convert them back to the real URL?

Examples

// Simplest version Endpoint.resolve('http://snurl.com/2luj3', function(url) {

alert(url);

});

// Used in the form below Endpoint.resolve(

document.getElementById('testurl').value, function(url) { alert(url); }

);

// Using the original URL to work out if it has changed Endpoint.resolve(

document.getElementById('testurl').value, function(url, orig) {

alert(url); alert(Endpoint.isRedirecting(url, orig));

}

);