From 6e5037ada79cf7b44258347e93065d25b06769b1 Mon Sep 17 00:00:00 2001
From: Marius Kircher <mskr@mailbox.org>
Date: Sun, 6 Jun 2021 08:51:57 +0200
Subject: [PATCH] ES6 Update

- async execute functions
- async undo functions
- ES6 module
---
 undo.js | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/undo.js b/undo.js
index b3527b8..b68e63a 100644
--- a/undo.js
+++ b/undo.js
@@ -7,7 +7,6 @@
  * 
  * MIT licensed.
  */
-(function() {
 
 // based on Backbone.js' inherits	
 var ctor = function(){};
@@ -52,17 +51,19 @@ Undo.Stack = function() {
 };
 
 extend(Undo.Stack.prototype, {
-	execute: function(command) {
+	execute: async function(command) {
 		this._clearRedo();
-		command.execute();
+		await command.execute();
 		this.commands.push(command);
 		this.stackPosition++;
 		this.changed();
 	},
-	undo: function() {
-		this.commands[this.stackPosition].undo();
-		this.stackPosition--;
-		this.changed();
+	undo: async function() {
+		if (this.canUndo()) {
+			await this.commands[this.stackPosition].undo();
+			this.stackPosition--;
+			this.changed();
+		}
 	},
 	canUndo: function() {
 		return this.stackPosition >= 0;
@@ -115,13 +116,4 @@ Undo.Command.extend = function(protoProps) {
 	return child;
 };
 	
-// AMD support
-if (typeof define === "function" && define.amd) {
-	// Define as an anonymous module
-	define(Undo);
-} else if(typeof module != "undefined" && module.exports){
-	module.exports = Undo 
-}else {
-	this.Undo = Undo;
-}
-}).call(this);
+export default Undo;
\ No newline at end of file