How to bind to the JS "hashchange" event.

hashchange.js

// Watches for changes in the URL hashbang and updates the #content pane accordingly
// Also updates the hash when we click on a link
function initHashChange() {
    // Bind an event to window.onhashchange that, when the hash changes, gets the
    // hash and adds the class "selected" to any matching nav link.
    $(window).hashchange(function(){
        var hash = window.location.hash.replace( /^#!\//, '' );

        if (hash == '') { return; }

        $('#content').children().hide();
        $('#' + hash + '-panel').show();


        // Highlights the item in the list, deselects all other routes
        $('.showpanel').removeClass('selected');
        $('#' + hash).addClass('selected');
    })

    // Since the event is only triggered when the hash changes, we need to trigger
    // the event now, to handle the hash the page may have loaded with.
    $(window).hashchange();
}