You know javascript? Please answer

The fast test really understands the JavaScript core closures and the scope. These five small scripts. Try to answer what is a reminder in each case that is not running in the console. You can then create a test file to easily check your answers. You ready?

if (!("a"in window)) {    var a = 1;}alert(a);

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

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

function  B (x, Y, a) {Arguments[2 ] =  10     ; alert (a);} B (1 , 2 , 3 );  

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

You know javascript? Please answer