ADVANCED JS

with Kyle Simpson

Compilation

A conversation between Compiler and Scope manager

    function foo(a) {
        console.log( a + b );
    }

    b = 2;

    foo( 2 ); // 4

Compiler: Hey Scope, do you have a function declaration for foo?

Scope manager: No.

Compiler: Please declare it.

Compiler: Hey Scope of foo, ever heard of formal parameter a?

Scope manager: No.

Compiler: Please declare it.

Formal declarations

Execution

A conversation between Engine and Scope

    function foo(a) {
        return a + b;
    }

    b = 2;

    foo( 2 ); // 4

Compiler: Hey Scope, I have a LHS reference for b, ever heard of it?

Scope manager: No... but I'm helpful so I created it for you.

Compiler: Thanks I guess, please assign 2 to b.

Compiler: Hey Scope, I have a RHS reference for foo, ever heard of it?

Scope manager: Sure, it's a function, here you go.

Compiler: Thanks, execute it!

Compiler: Hey Scope of foo, I have a LHS ref. for a, ever heard of it?

Execution

A conversation between Engine and Scope

    function foo(a) {
        return a + b;
    }

    b = 2;

    foo( 2 ); // 4

Scope manager: Well yes compiler declared it a millisecond ago. Voila!

Compiler: Merci beaucoup! Please assign 2 to a.

Compiler: Hey Scope of foo, I have a RHS ref, for a, ever heard of it?

Scope manager: Yup it's 2.

Compiler: Hey Scope of foo, I have a RHS ref. for b, ever heard of it?

Scope manager: Go fish.

Compiler: Hey upper Scope of foo, I have a RHS trf.  for b, ever heard of it?

Scope manager: Sure, it's 2.