How do I disable and re-enable a button in with javascript?

I can easily disable a javascript button, and it works properly. My issue is that when I try to re-enable that button, it does not re-enable. Here's what I'm doing:

<script type="text/javascript">
    function startCombine(startButton) {

        startButton.disabled = 'true';

        startButton.disabled = 'false';

    }
</script>
<input type='button' id='start' value='Combine Selected Videos'
onclick='startCombine(this);'>

Why isn't this working, and what can I do to make it work?

Solution 1:

true and false are not meant to be strings in this context.

You want the literal true and false Boolean values.

startButton.disabled = true;

startButton.disabled = false;

The reason it sort of works (disables the element) is because a non empty string is truthy. So assigning 'false' to the disabled property has the same effect of setting it to true.

Solution 2:

<script>
function checkusers()
{
   var shouldEnable = document.getElementById('checkbox').value == 0;
   document.getElementById('add_button').disabled = shouldEnable;
}
</script>