Question

For example, when you use jQuery('someDiv');, it’s a function, but you can also use jQuery.ajax(...);.

How is it possible?

Answer 1

In JavaScript, functions themselves are objects.

var x = function () {};
x.foo = "bar";

console.log(x.foo); // bar

EDIT:

To add onto this:

var x = function () {
    return 'foo';
};
x.bar = function () {
    return 'baz';
};

So now:

console.log(x()); // foo
console.log(x.bar()); // baz