正式支持在HTML select中添加两个onChange事件处理程序吗？

Question

I was puzzling over the best way to have a second action happen when a drop-down box is changed. I didn't expect the following to work, I expected the dynamically added change() to replace the static one, but it did work (tested in Firefox, Chrome and Opera 12 so far).

Is this officially part of any of the HTML standards, or did I just get lucky and it might break in a future release or an older browser?

<select id="testing" onChange="alert('first');">
<option></option>
<option value="1">One</option>
<option value="2">Two</option>
</select>

<script>
$('#testing').change(function(){
    alert("second");
    });
</script>

(For context, I have a Handlebars helper function making the <select> HTML, with its own onChange , which is used to hide/show an "other:" text box; now I want to perform some special actions when certain values are selected, and ideally I want to continue to use the handlebars helper, as-is.)

Answer 1

Short answer

Yes, it is officially supported ; this is fine and won't break until the standards change.

Long(er) answer

The "static" on[event] ( onchange , in this case) handlers are called separately from the "dynamic" handlers added using addEventListener or similar (jQuery normalizes this for you).

In fact, many Google Web frontends use the on[event] -style handlers in their JavaScript.

Further reading:

https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Event_handlers