Values in parentheses after javascript function

Question

I'm trying to re-purpose some Javascript code I found linked in an answer on SO. But I would like to understand its syntax better first. Its outline is:

(function (root, ns, factory) {
    // some code
} (window, 'detectZoom', function() {
    // some more code
}));

See accepted answer in this post for the reference to the full code.

I understand how the end-result is achieved, but I don't quite know how the inner (...) block relates to the first, or what the comma separated list inside it tells the compiler.

Can someone explain? Thanks.

Answer 1

What you have is a immediately-invoked function expression (IIFE). If you strip out all the arguments you're just left with this:

(function () {
    // some code
}());

The function expects three arguments:

(function (root, ns, factory) {
    // some code
}());

And you pass it three arguments:

(function (root, ns, factory) {
    // some code
} (window, 'detectZoom', function() {
    // some more code
}));

One of those arguments, factory, happens to be a function.