javascript trigger change event
There's a couple of ways you can do this. If the onchange listener is a function set via the element.onchange property and you're not bothered about the event object or bubbling/propagation, the easiest method is to just call that function:
element.onchange();
If you need it to simulate the real event in full, or if you set the event via the html attribute or addEventListener/attachEvent, you need to do a bit of feature detection to correctly fire the event:
if ("createEvent" in document) {
var evt = document.createEvent("HTMLEvents");
evt.initEvent("change", false, true);
element.dispatchEvent(evt);
}
else
element.fireEvent("onchange");