What is the difference between setting properties to the global object and the window object?

this.f = function() {};
wind开发者_StackOverflow中文版ow.d = function() {};

d();
f();

Any difference?

Not if it's run barely (e.g. not within special functions etc.). Because then this === window.

In constructor functions etc. this has another meaning, so then it matters:

function x() {
    this.a = 123;
}

Now,

• x() would set window.a to 123
• var test = new x() would set test.a to 123.