On - [removed].hash - Change?

Question

I am using Ajax and hash for navigation.

Is there a way to check if the window.location.hash changed like this?

http://example.com/blah#123 to http://example.com/blah#456

It works if I check it when the document loads.

But if I have #hash based navigation it doesn't work when I press the back button on the browser (so I jump from blah#456 to blah#123).

It shows inside the address box, but I can't catch it with JavaScript.

Answer 1

I used a jQuery plugin, HUtil, and wrote a YUI History like interface on top of it.

Check it out once. If you need help I can help.

Answer 2

Note that in case of Internet Explorer 7 and Internet Explorer 9 the if statment will give true (for "onhashchange" in windows), but the window.onhashchange will never fire, so it's better to store hash and check it after every 100 millisecond whether it's changed or not for all versions of Internet Explorer.

    if (("onhashchange" in window) && !($.browser.msie)) {
         window.onhashchange = function () {
              alert(window.location.hash);
         }
         // Or $(window).bind( 'hashchange',function(e) {
         //       alert(window.location.hash);
         //   });
    }
    else {
        var prevHash = window.location.hash;
        window.setInterval(function () {
           if (window.location.hash != prevHash) {
              prevHash = window.location.hash;
              alert(window.location.hash);
           }
        }, 100);
    }

EDIT - Since jQuery 1.9, $.browser.msie is not supported. Source: http://api.jquery.com/jquery.browser/

Answer 3

There are a lot of tricks to deal with History and window.location.hash in IE browsers:

• As original question said, if you go from page a.html#b to a.html#c, and then hit the back button, the browser doesn't know that page has changed. Let me say it with an example: window.location.href will be 'a.html#c', no matter if you are in a.html#b or a.html#c.

• Actually, a.html#b and a.html#c are stored in history only if elements '<a name="#b">' and '<a name="#c">' exists previously in the page.

• However, if you put an iframe inside a page, navigate from a.html#b to a.html#c in that iframe and then hit the back button, iframe.contentWindow.document.location.href changes as expected.

• If you use 'document.domain=something' in your code, then you can't access to iframe.contentWindow.document.open()' (and many History Managers does that)

I know this isn't a real response, but maybe IE-History notes are useful to somebody.

Answer 4

Firefox has had an onhashchange event since 3.6. See window.onhashchange.

Answer 5

Ben Alman has a great jQuery plugin for dealing with this: http://benalman.com/projects/jquery-hashchange-plugin/

If you're not using jQuery it may be an interesting reference to dissect.

Answer 6

Another great implementation is jQuery History which will use the native onhashchange event if it is supported by the browser, if not it will use an iframe or interval appropriately for the browser to ensure all the expected functionality is successfully emulated. It also provides a nice interface to bind to certain states.

Another project worth noting as well is jQuery Ajaxy which is pretty much an extension for jQuery History to add ajax to the mix. As when you start using ajax with hashes it get's quite complicated!