Question

var a = 1;
function b() {
    a = 10;
    return;
    function a() {}
}
b();
alert(a);

How is the output of 1 displayed for a? What does the

return;
function a() {}

within the function body perform?

Answer 1

You code is misleading and in a style that makes people think execution order matters. The standard JavaScript engine these days will take that and reformat prior to running it to:

var a = 1,
b = function() {
    var a = function() {};
    a = 10;
    return;
};
b();
alert(a);

Now you can understand what is actually happening. “a” is declared again inside the function “b” so there is actually two “a” variables now. One is “window.a” and the other one is “b var a” but NOT “b.a” because its not accessible outside of the closure or function.

In other words, you get what you code for.

Please make your code readable and don’t confuse the point.