Why does this JavaScript example point to the global object (Window)?

Question

function F() {
    function C() { 
        return this;
    } 
    return C();
} 
var o = new F();

Answer 1

Break down the component elements.

Suppose you were to do this:

function C() {
    return this;
}
var o = C();

There is clearly no object context here, so this is window.

Wrapping that setup in a constructor doesn't change the fact that there isn't any object involved in the context of a straightforward call to C().