How to enable Submit Button after filling out the required fields? I have created custom Content Type and I would like to disable the submit button, till the user has filled out all the required fields.

I should enable the submit button, once the user fills out the required fields, how do i achieve this?
check out #states visible #states invisible in drupal.

http://api.drupal.org/api/examples/form_example!form_example_states.inc/function/form_example_states_form/7

http://api.drupal.org/api/drupal/includes!common.inc/function/drupal_process_states/7