added ajax compatibility

Im running this JS in my own custom file, but for those of you who want this to function in this plugin while using ajax you can change your disable-gf-fields.js file to the following code this can be done by editing the plugin file in through the WP plugin after installation by going to your admin screen and then plugins, then click edit next to this plugin and select the file . ..or you can just edit the js file before installation. anyway, gravity forms has a simple after render hook to allow for things to take place after any ajax or other renders of the form so you can just rerun the code any time the form is rendered by replacing this files code with this.

jQuery(document).ready(function($){
	$(".disabled input").attr('disabled','true');
	$(".readonly input").attr('readonly','true');
});

$(document).bind('gform_post_render', function(){
	$(".gform_wrapper .readonly input").attr("readonly", true);
	$(".gform_wrapper .disabled input").attr("disabled", true);
});

then the plugin will work with ajax as well.

THIS WILL ONLY WORK WITH READONLY to retain field data if you are pre-populateting the field dynamically!
Disabled fields do not pass information to the server and as such do not retain any pre populated data from a query string or shortcode ect. with the ajax call such as after a failed submission or page change and will fall back to their default state.

..you can however just set the default value of a disabled field if it is a constant value to be pre-populated, and it will work fine. but the data still will not be submitted with the form. you should use readonly to have the data passed.