Do you think you understand JavaScript?

English Original address: http://dmitry.baranovskiy.com/post/91403200
Dmitry Baranovskiy's Blog contains an article (http://dmitry.baranovskiy.com/post/91403200) with five small pieces of code to test the understanding of JavaScript's core, closures, and scopes. Let's try to give the output of the alert statement first. Then build a test file to check your answers.

One

JavaScript Code

if inch window)) {    var a = 1;} alert (a);

Two

JavaScript Code

var a = 1,    function  A (x) {        && A (--x);    }; alert (a);

Three

JavaScript Code

function A (x) {    return x * 2;} var A;alert (a);

Four

JavaScript Code

function b (x, Y, a) {    arguments[2] = ten;    alert (a);} B (1, 2, 3);

Five

JavaScript Code

function A () {    alert (this);} A.call (null);

Do you think you understand JavaScript?