How can I trigger an onchange event manually? [duplicate]

How can I trigger an onchange event manually? [duplicate]

This question already has an answer here:

How to trigger event in JavaScript?

17 answers

I’m setting a date-time textfield value via a calendar widget. Obviously, the calendar widget does something like this :
document.getElementById(‘datetimetext’).value = date_value;

What I want is :
On changing value in the date-time textfield I need to reset some other fields in the page. I’ve added a onchange event listener to the datetimetext field which is not getting triggered, because I guess onchange gets triggered only when the element gets focus & its value is changed on losing focus.
Hence I’m looking for a way to manually trigger this onchange event (which I guess should take care of checking the value difference in the text field).
Any ideas ?

Solutions/Answers:

Solution 1:

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");

Solution 2:

MDN suggests that there’s a much cleaner way of doing this in modern browsers:

// Assuming we're listening for e.g. a 'change' event on `element`

// Create a new 'change' event
var event = new Event('change');

// Dispatch it.
element.dispatchEvent(event);

Solution 3:

For those using jQuery there’s a convenient method: http://api.jquery.com/change/