How to use JQuery with Master Pages?

EDIT

As @Adam points out in the comments, there is a native jQuery mechanism that basically does the same thing as the hack in my original answer. Using jQuery you can do

 $('[id$=myButton]').click(function(){ alert('button clicked'); }); 

My hack was originally developed as a Prototype work around for ASP.NET and I adapted it for the original answer. Note that jQuery basically does the same thing under the hood. I recommend using the jQuery way, though, over implementing my hack.

Original answer left for comment context

When you use a master page, ASP.NET mangles the names of the controls on the dependent pages. You’ll need to figure out a way to find the right control to add the handler to (assuming you’re adding the handler with javascript).

I use this function to do that:

function asp$( id, tagName ) {
    var idRegexp = new RegExp( id + '$', 'i' );
    var tags = new Array();
    if (tagName) {
        tags = document.getElementsByTagName( tagName );
    }
    else {
        tags = document.getElementsByName( id );
    }
    var control = null;
    for (var i = 0; i < tags.length; ++i) {
       var ctl = tags[i];
       if (idRegexp.test(ctl.id)) {
          control = ctl;
          break;
       }
    }

    if (control) {
        return $(control.id);
    }
    else {
        return null;
    }
}

Then you can do something like:

jQuery(asp$('myButton','input')).click ( function() { alert('button clicked'); } );

where you have the following on your child page

<asp:Button ID="myButton" runat="server" Text="Click Me" />