How to check if page exists using JavaScript

Question

I have a link: <a href="http://www.example.com">Hello</a>.

When someone clicks the link I'd like to check via JavaScript if the page the href-attribute points to exists or not. If the page exists the browser redirects to that page ("www.example.com" in this example) but if the page doesn't exist the browser should redirect to another URL.

Answer 1

It depends on whether the page exists on the same domain or not. If you're trying to determine if a page on an external domain exists, it won't work – browser security prevents cross-domain calls (the same-origin policy).

If it is on the same domain however, you can use jQuery like Buh Buh suggested. Although I'd recommend doing a HEAD-request instead of the GET-request the default $.ajax() method does – the $.ajax() method will download the entire page. Doing a HEAD request will only return the headers and indicate whether the page exists (response codes 200 - 299) or not (response codes 400 - 499). Example:

$.ajax({
    type: 'HEAD',
    url: 'http://yoursite.com/page.html',
success: function() {
        // page exists
},
error: function() {
        // page does not exist
}
});

See also: http://api.jquery.com/jQuery.ajax/