Question

When a function is attached to an object and called:

function f() { return this.x; } var o = {x: 20}; o.func = f; o.func(); //evaluates to 20 

this refers to the object that the function was called as a method of. It’s equivalent to doing f.call(o).

When the function is called not as part of an object, this refers to the global object. How do I check if a function is being called from a non-object context? Is there any standard keyword to access the global object? Is the only way to do it something like this?

globalobj = this; function f() { if (this == globalobj) doSomething(); } 

Note: I have no particular use case in mind here – I actually am asking about this exact mechanism.

Answer 1

The global object is actually the window so you can do

if (this === window)