Firefox fires on choose, not on change

[Rain_Lover]

Consider this:

<input type="file" id="filePicker">
<script>
 document.getElementById('filePicker').onchange = function() {
  alert('Hi!');
 };
</script>

Even if you choose the same file and the filePicker value doesn't change, you'll see the alert box in Firefox. Any solutions?

[Fotiman]

One option might be to store the previous value in a variable and compare it to see if the value really changed. Something like:

var filePicker = document.getElementById('filePicker'),
  prevValue = filePicker.value;

filePicker.onchange = function(e) {
  if (prevValue !== this.value) {
    // true change event
    prevValue = this.value;
    alert('Hi!');
  }
};

[Fotiman]

Side note:
[developer.mozilla.org...]

Different browsers do not always agree whether a change event should be fired for certain types of interaction.

[Rain_Lover]

Perfect! But I wonder if it's necessary to add the e parameter to the function.

[Fotiman]

No, it's not. Just remove it. :)