You-dont-know-js: On chapter 5 page 50. Example code don't show me nothing

[jhorgint]

function foo() {
var a = 2;
function baz() {
console.log( a ); // 2
}
bar( baz );
}
function bar(fn) {
fn(); // look ma, I saw closure!
}

I don't know what is happening!!!, I have tried on JS Bin, jsfiddle and on Chrome .
Sorry, I'm new on JS and don't figure out what is happening

[getify]

The code snippet prints "2". The inner function baz closes over the variable a that is inside foo. That baz function reference is passed to the function bar which is a different scope. However, the a is still accessible by baz because of closure.

[jhorgint]

Thanks a lot, your argument is right but I don't get it run on my PC, I'm doing something wrong for sure.

[jhorgint]

Just need to call the "foo();" function, hahaha....

[getify]

Ah... sorry for the confusion.