Scope

gistfile1.js

'use strict';


console.log('--------- Scope:');

(function () {

    var a = 1;
    for (var a = 0; a < 10; ++a) {}
    console.log('1.1:', a); // -> 10


    {
        var b = 1;
    }
    console.log('1.2:', b); // -> 1


    var c_fn = function () {
        var c = 1;
    };
    c_fn();
    //console.log('1.3:', c); // -> ReferenceError

})();

console.log('--------- Lexical scoping:');

(function () {

    var a = 1;
    var a_fn = function () {
        return a;
    };

    console.log('2.1:', a_fn()); // -> 1

    (function (fn) {
        var a = 2;
        console.log('2.2:', fn()); // -> 1
    })(a_fn);

    (function (fn) {
        a = 3;
        console.log('2.3:', fn()); // -> 3
    })(a_fn);

    console.log('2.4:', a_fn()); // -> 3


    var b = [1, 2, 3, 4],
        b_i = 0;
    
    for(; b_i < b.length; ++b_i) {
        b[b_i] = function () { return b_i; };
    }
    console.log('2.5:', b[0]()); // -> 4

})();