postforms.js

/*
Show a progress element for any form submission via POST.
Prevent the form element from being submitted twice.
*/
(function ( win, doc ) {
	'use strict';
	if ( !win.addEventListener ) {
		// doesn't cut the mustard.
		return;
	}
	var submitting = false;
	function checkForm( event ) {
		if ( submitting ) {
			event.preventDefault();
		}
		else {
			if ( event.target.method === 'post' ) {
				submitting = true;
				event.target.appendChild( doc.createElement('progress') );
			}
		}
	}
	doc.documentElement.addEventListener( 'submit', checkForm, false );
}( this, this.document ));