Javascript multiple assignment statement

Question

I saw that line in some code

window.a = window.b = a;

How does it work?

Does the following always return true?

win

Answer 1

The a and b properties on the window are being assigned to the value of a. Yes, if this code is executed in the global scope, a and window.a are the same.

var a = "foo";

//window.a and a are the same variable
window.a = "bar";
a; //bar

function f(){
    var a = "notfoo";

    //window.a is a different variable from a, although they may take the same value
    window.a = "baz";
    a; //notfoo
}