Using .apply with Strings in JavaScript

Ran into an interesting issue with trying to pass a primitive String variable in as the context during an .apply call. The String primitive was autoboxed to a String object.

Here is an example of this happening:

function boxing() { return this; }

var test = 'test';

boxing.apply(test) === 'test'; // will return false

When the test variable gets passed in as the context using the apply function, it gets boxed to the actual String object, not the primitive.

The way to have this autoboxing not occur, is to put the:

use strict;

declaration at the top of your file. This will prevent the vm from autoboxing the context in the .apply function.