Simulating href click

i need to simulated having clicked on a link with JavaScript. As you will see in my stripped down example the resulting function from the click is a window.addEvent() action. Thanks for the help.

js code -

window.addEvent('domready', function() {
     expandCollapse();
}

function expandCollapse(){
     $('expand').addEvent('click', function(){
          // do something
     }
}

Code (markup):

html code -

<a id="expand" href="javascript:void(0);">open all</a>

Code (markup):

i have tried this but id didnt work -

document.getElementById('expand').click();

Code (markup):

What is the code to make the window.addEvent() fire? *expand* must be part of it. Thank you.

 

Thanks to Fang -

Working Solution -

function fireOnclick(objID) {
var target=document.getElementById(objID);
if(document.dispatchEvent) { // W3C
    var oEvent = document.createEvent( "MouseEvents" );
    oEvent.initMouseEvent("click", true, true,window, 1, 1, 1, 1, 1, false, false, false, false, 0, target);
    target.dispatchEvent( oEvent );
    }
else if(document.fireEvent) { // IE
    target.fireEvent("onclick");
    }    
}

Code (markup):