Question

I need to have some information about the scoping in JavaScript. I know that it supports lexical (static) scoping, but, does not it support dynamic scoping as well?

Answer 1

I think you’re confused because Javascript uses static scoping but at function-level, not at block level like usual structured languages.

var foo = 'old'; if (true) {var foo = 'new';} alert (foo == 'new') 

So be careful, blocks don’t make scope! That’s why you sometimes see loops with functions inside just to enable variables whose scope is inside an iteration:

functions = []; for(var i=0; i<10; i++) {    (function(){        var local_i = i;        functions[local_i] = function() {return local_i;}    })(); } functions[2]() // returns 2 and not 10