Question

I have a JavaScript library that updates a hidden <textarea> HTML element with some data based on some things.

In my (JavaScript) application I’d like to know when these updates occur without having to go through the existing library code.

I was hoping there was an event for this, but apparently not.

How would I listen for changes of the textarea?

Changes can be as simple as document.getElementById("myTextarea").value = "hello";

EDIT I will be using FireFox only, since this code will only be part of a test suite I’m building.

Answer 1

If you control the Javascript library you mention, I would say the easiest way would be to manually trigger the change event every time you change a field’s value.

I think this is how it’s done in JQuery: Events/change Otherwise, a simple document.getElementById('myTextarea').onchange() might work as well.

If you have many calls, you could wrap the changing of the value, and the triggering of the event into a changeFormElement(id, value) function.

This requires, of course, that you can modify every instance of when a textarea is changed. If that is given, this is probably the most elegant way.