Question

Edit: this question was asked due to my misunderstanding. Proceed with caution, as reading it might waste your time.

I thought call and apply would execute a function given a set of arguments, but I’m getting confusing test results. See my test code:

window.z = 0;
(function(){++(window.z)}).call(this, 1, 2, 3)

I would expect z to be 3 after execution. However, z is 1.

(function(){++(window.z)}).apply(this, [1, 2, 3])

Same here. z == 1;
I tried simply logging the input argument as well:

var x = function(y){console.log(y);}
x.call(this, 1, 2, 3);

Result? Only 1 is logged.
What am I doing wrong here?

(Tested in Chrome and Firefox with Firebug.)

Answer 1

Both call and apply only call the function once. The difference is how the arguments to the invocation are passed.

With call, each parameter after the context (first parameter), is a parameter. With apply, the second parameter should be an array like object of parameters (the first parameter still provides the context).

function foo(a, b, c) {

};

foo.call(this, 1, 2, 3); // a == 1, b == 2, c == 3;
foo.apply(this, [1,2,3]); // a == 1, b == 2, c == 3;

If you want to call the function multiple times, you can accomplish this by simply putting the call in a loop.