jQuery disable/enable submit button

Question

I have this HTML:

How can I do something li

Answer 1

The answers above don't address also checking for menu based cut/paste events. Below's the code that I use to do both. Note the action actually happens with a timeout because the cut and past events actually fire before the change happened, so timeout gives a little time for that to happen.

$( ".your-input-item" ).bind('keyup cut paste',function() {
    var ctl = $(this);
    setTimeout(function() {
        $('.your-submit-button').prop( 'disabled', $(ctl).val() == '');
    }, 100);
});