When is the next article coming out? I look forward to it!

The first version of that approach, the latency was too high because sending data over TCP on a thin client computer takes to long. The mouse pointer movement trailed quite a way behind your finger movement.

The current version still uses XMLSocket, but now the pointer is drawn to the screen by the socket server application, so it doesn’t suffer the TCP delay.

JavaScript is a special case, since in JavaScript, *every method* is already a Strategy. In JavaScript you can choose to swap out any method at runtime, dynamically build new classes, or modify the prototype of existing classes for AOP effects. In short, far from not requiring the pattern I suggest in this article, JavaScript implements it by default. I would argue that since the Strategy pattern is already so well supported in JavaScript, that’s extra reason not to resort to MI and mixins.

Here’s an example - supposing you are building an object that at some point needs to alter the value of a string in a way that the user of the class wants to control. You can provide the string editing as a Strategy or a mixin.

A nice trick in JavaScript is to provide a default Strategy function ‘this.stringEditor(str)’ and whenever you call it, use the code ‘this.stringEditor.call(this, str)’, i.e. by using the ‘call’ method that exists on all function objects. If client code needs to supply new string editing behaviour, they can write a new function and replace the existing ‘this.stringEditor’ on a per-object basis or for a whole class using the prototype. If the bit of behaviour is more complex (e.g. it has multiple configuration options and helper functions) then ‘this.stringEditor’ can be replaced with an object that contains a ‘call(parent, str)’ method. This lightweight Strategy pattern lets you get all the benefit of Strategy objects, without the overhead when you’re not using them.

Now consider if you’d used a mixin. In the simple case of one function editString, it’s fine. When your mixin starts needing complex state and helper functions, these pollute the object’s namespace and make it difficult or impossible to change the Strategy at runtime.

That said, some JavaScript frameworks make great use of mixins for providing core functionality to classes. Prototype’s Enumerable mixin is a perfect example. It is so successful because it is providing core functionality to an object, and there is no way you’d want to change the way an object Enumerates its children at runtime.