How do I override an object method in JavaScript?

Why was JavaScript designed such that "this" refers to the object invoking a function, rather than the object containing the function invoked?

• In other programming languages the "this" keyword, or its equivalent, typically refers to the object in which a method is defined.  In Javascript "this" can change depending on what calls a function and whether or not you invoke a function using method syntax.  It often requires workarounds to get the typical behavior you'd expect.  I assume this was a deliberate design decision, but was wondering why it was made, and if it has any benefits. More information (but not an answer as to why) available here: http://stackoverflow.com/questions/80084/in-javascript-why-is-the-this-operator-inconsistent

• Answer:

  I think Alan Storm's reply on SO answers the question, albeit at length. It's useful when you want to use a generic function for multiple objects: var s, c, o1, o2; s = function (newStatus) { this.status = newStatus.toUpperCase() || "NONE"; return this; // allow method chaining, ala jQuery }; c = function () { console.log(this.status); return this; }; o1 = { status: "", setStatus: s, log: c }; o2 = { status: "", update: s writeStatus: c }; o1.setStatus("object 1").log(); // "OBJECT 1" o2.update("hello, world!").writeStatus(); // "HELLO, WORLD!" // Even works on anonymous objects: ({ status: "INIT", say: c }).say(); // "INIT" Regarding the "requires workarounds to get the typical behavior you'd expect", this is only true if you expect it to work like a classical language. JavaScript is not a classical language so getting out of that mindset will make things easier on you :-)