Javascript – What would be a better name for Javascript’s “this”


I'm coming from a Java background, with its class-based inheritance model, trying to get my head around Javascript's prototype-based inheritance model. Part of what is throwing me off, I think is that I have Java's meaning of "this" solidly in mind – and Javascript's "this" is a very different beast. I understand that Javascript's "this" always refers to the function's caller, not the scope in which the function was defined – I mean, I have read that and understand superficially what it means. But I would like to have the understanding more deeply, and I think having another name for it would help. How do you think about JS "this"? Do you make a mental replacement every time you run across it? If so – what word or phrase do you use?

Best Solution

this might be reasonably renamed to context in Javascript.

It's really referring to an execution context for the current scope, and while that context can be an instance of a class, it certainly doesn't have to be — it can be any object at all, and it can be modified at run-time.

Proof that there is no guarantee whatsoever that a "method" in Javascript is operating on an instance of the "class" in which it is defined:

function Cat(){

     this.texture = 'fluffy';

     this.greet = function(){
         alert("Pet me, I'm " + this.texture);

 var cat = new Cat();

 // Default to using the cat instance as the this pointer
 cat.greet(); // Alerts "Pet me, I'm fluffy"

 // Manually set the value of the this pointer!{texture: 'scaly'});  // Alerts "Pet me, I'm scaly"

It's important to note there that the value of the this object is completely independent of where the containing function is defined.