CODEWITHSUNDEEP
javascriptthisdom-events
Hcabnettek
Hcabnettek

Reputation: 12928

Can I change the context of javascript "this"?

var UI$Contract$ddlForm_change = function() {

    //'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?

Upvotes: 36

Views: 36858

Answers (3)

James
James

Reputation: 111910

No, it's not possible.

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

Upvotes: 53

Daniel Roseman
Daniel Roseman

Reputation: 599590

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.

Upvotes: 12

the.jxc
the.jxc

Reputation: 3461

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.

Upvotes: 7

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