javascript detect a click code example

Example 1: how to detect a button click in javascript

if(document.getElementById('button').clicked == true)
{
   alert("button was clicked");
}

Example 2: javascript perform click

function eventFire(el, etype){
  if (el.fireEvent) {
    el.fireEvent('on' + etype);
  } else {
    var evObj = document.createEvent('Events');
    evObj.initEvent(etype, true, false);
    el.dispatchEvent(evObj);
  }
}