Attach a Javascript function to an OOTB ribbon button - sharepoint

Question

I want to attach a custom javascript function to the out of the box "Download a copy" ribbon button. This is to provide analytics for file downloads done through the ribbon button.
I tried this code, but it doesn't seem to work:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.min.js">
</script>
<script>
_spBodyOnLoadFunctionNames.push("Trackdownloads");
function Trackdownloads(){
debugger;
$("a[id='Ribbon.Documents.Copies.Download-Large']").live( "click",
function() {
alert('hello');
}
);
}
</script>
Any idea how to get this to work?

Answer 1

Found a solution to my problem.
Actually, attaching a javascript function to the button is not the right way to implement this.
The correct implementation is to replace the OOTB button with a custom button, and call a custom javascript function to carry out the desired action.
http://msdn.microsoft.com/en-us/library/ff407619.aspx

Answer 2

If you do want to override a button in the ribbon. Creating a custom Page Component is a good idea. Example:
Type.registerNamespace('Company.Project.Ribbon.PageComponent');
Company.Project.Ribbon.PageComponent = function (PageComponentId) {
this._pageComponentId = PageComponentId;
Company.Project.Ribbon.PageComponent.initializeBase(this);
}
Company.Project.Ribbon.PageComponent.prototype =
{
_pageComponentId: "PageComponentIDHolder",
getId: function () {
return this._pageComponentId;
},
init: function () {
this._myCommandList = ['DownloadCopy'];
this._myHandledCommands = {};
this._myHandledCommands['DownloadCopy'] = Function.createDelegate(this, this.CMD1_Handler);
},
getFocusedCommands: function () {
return this._myCommandList;
},
getGlobalCommands: function () {
return this._myCommandList;
},
canHandleCommand: function (commandId) {
var canHandle = this._myHandledCommands[commandId];
if (canHandle)
return true;
else
return false;
},
handleCommand: function (commandId, properties, sequence) {
return this._myHandledCommands[commandId](commandId, properties, sequence);
},
isFocusable: function () {
return true;
},
CMD1_Handler: function (commandId, properties, sequence) {
alert('Download a copy-button was clicked');
}
}
Company.Project.Ribbon.PageComponent.registerClass('Company.Project.Ribbon.PageComponent', CUI.Page.PageComponent)
NotifyScriptLoadedAndExecuteWaitingJobs("/_layouts/custompagecomponents/PageComponent.js");
function init2() {
var instance = new Company.Project.Ribbon.PageComponent("ComponentID");
SP.Ribbon.PageManager.get_instance().addPageComponent(instance);
}
function init1() {
ExecuteOrDelayUntilScriptLoaded(init2, 'sp.ribbon.js');
}
ExecuteOrDelayUntilScriptLoaded(init1, '/_layouts/custompagecomponents/PageComponent.js');