Can I change the context of javascript "this"?

Question

var UI$Contract$ddlForm_change = function() {
    debugger;
    //'this' is currently the drop down that fires the event
    // My question is can I change the context so "this" represents another object? 

this = SomeObject;
// then call methods on the new "this"

this.someMethod(someParam);

};

is this possible? Thanks, ~ck in San Diego

Answer 1

Not sure if it's best practice, but you can store a reference to the old "this" with:

_this = this;
// Do some stuff
_this.someMethod();

Answer 2

No, it's not possible.

You can call a method with a specified context (using method.apply()/method.call()) but you cannot re-assign the keyword, this.

Answer 3

J-P is correct. This is not possible. Refer to the JavaScript language specification document ECMA-262. You can download the standard from here:

http://www.ecma-international.org/publications/standards/Ecma-262.htm

The file is ECMA-262.pdf and on page 39, section 10.1.7.

10.1.7 This

There is a this value associated with every active execution context. The this value depends on the caller and the type of code being executed and is determined when control enters the execution context. The this value associated with an execution context is immutable.

Note "is immutable". i.e. cannot be changed.

Answer 4

You can't change what this refers to from inside the function.

However, you can call a function in a specific context - so that this refers to a specific object - by using call or apply.