trigger change event javascript code example

Example 1: how to add onclick event in javascript

var element = document.getElementById("elem");
element.onclick = function(event) {
  console.log(event);
}

Example 2: js input trigger change event when set value with js

var el = document.getElementById('changeProgramatic');
el.value='New Value'
el.dispatchEvent(new Event('change'));

Example 3: 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");

Example 4: javascript remove event listener after bind

var someEventHander=function(){
	console.log("do something");
}
var handlerCopy=someEventHandler.bind(var1,var2)
//add listener
document.getElementById("someid").addEventListener('click',handlerCopy,true);
//remove listener 
document.getElementById("someid").removeEventListener('click',handlerCopy,true);