[development] Disabling a form button after a click doesn't work?

I'm trying to disable the submit button of my form and set the value to "waiting.." after someone clicks. In my javascript I'm doing: $("#node-form .form-submit")[0].disabled=true However with that added, the form can never be submitted successfully --it throws you back to the form but without any visible errors. (I take it out and it works) Any suggestions?