Question

In Javascript I have simple test code:

function x(a, b) {
  alert(a);
  alert(b);
}

var c = [1,2];
x(c);

which send an argument c to function x() as one argument, assigned to a and b stays undefined :-/

How can I send an array as multiple arguments to a function, not as one array?

Answer 1

Check out apply.

In your case (since you aren’t using this in the function), you can simply pass window (or this) as the “this” argument:

x.apply(this, [1, 2]);

Example: http://jsfiddle.net/MXNbK/2/

Per your question about passing null as the “this” argument, see MDN’s comment in the linked article on the “this” argument:

Note that this may not be the actual value seen by the method: if the
method is a function in non-strict mode code, null and undefined will
be replaced with the global object, and primitive values will be
boxed.