javascript function to check if a form has inputs that have been changed

formIsDirty()

/**
 * Determines if a form is dirty by comparing the current value of each element
 * with its default value. Nicely done on StackOverflow: https://stackoverflow.com/a/155812/1558564
 *
 * @param {Form} form the form to be checked.
 * @return {Boolean} true if the form is dirty, false if it's not.
 */
function formIsDirty(form) {
	for (var i = 0; i < form.elements.length; i++) {
		var element = form.elements[i];
		var type = element.type;
		if (type == "checkbox" || type == "radio") {
			if (element.checked != element.defaultChecked) {
				return true;
			}
		}
		else if (type == "hidden" || type == "password" ||
			type == "text" || type == "textarea" || type == "email") {
			if (element.value != element.defaultValue) {
				return true;
			}
		}
		else if (type == "select-one" || type == "select-multiple") {
			for (var j = 0; j < element.options.length; j++) {
				if (element.options[j].selected !=
					element.options[j].defaultSelected) {
					return true;
				}
			}
		}
	}
	return false;
}