Angular 1 directive that allows the user to cancel a text input change with 'Escape'

cdz-cancellable.js

/**
 * This directive allow the user to 'cancel' an input with the 'Esc' key.
 * Basically this saves the input value on focus, and set it back to this 'old' value whenever the user hit 'Esc'.
 * Additionally, if the input value did not change when the user hits 'Esc', then the whole input value is selected.
 *
 * @usage <element data-cdz-cancellable contenteditable></element>
 */
app.directive('cdzCancellable', function() {
	return {
		restrict: 'A',
		require: 'ngModel',
		link: function(scope, elm, attrs, ngModelCtrl) {
			if (attrs.type === 'radio' || attrs.type === 'checkbox') {
				return;
			}

			var oldValue = null;

			function saveCurrentElementValue() {
				if (isCdzNumericNode(elm)) { //When used with the autoNumeric library
					oldValue = elm.autoNumeric('get');
				}
				else {
					oldValue = elm.val();
				}
			}

			elm.bind('focus', function() { //On focus, save the initial value
				scope.$apply(function() {
					saveCurrentElementValue();
				});
			});

			elm.bind('keyup', function(event) { //On 'Esc' key, set back the initial value
				var key = (typeof event.which === "undefined")?event.keyCode:event.which;
				if (key === cdzUtils.keyCode.Esc) {
					event.preventDefault();

					if ("" === oldValue) {
						oldValue = 0;
					}

					ngModelCtrl.$setViewValue(oldValue);
					scope.$apply(); //Launch a $digest
					ngModelCtrl.$render();

					this.select(); //Auto select the input text to facilitate its edition

					scope.$broadcast('escapePressed');
				}
			});

			var onEnterPressedOff = scope.$on('enterPressed', function(event) { //Important : update the saved value if the form is validated
				saveCurrentElementValue();
			});

			scope.$on('$destroy', function() {
				elm.unbind('focus');
				elm.unbind('keyup');
				onEnterPressedOff();
			});
		}
	};
});