Javascript quiz

Link: http://perfectionkills.com/javascript-quiz/

You've got 4 answers wrong (#1, #3, #5, #14).
Very good, but not quite there yet.

错了4道题, GG,

1.

(function(){
  return typeof arguments;
})();

这里 arguments 应该是一个参数的对象, 不是数组, 且次对象的值和参数值绑定, 例如

(function b(a) {
  arguments[0] = 2;
  return a;
})(1)
输出 2

3.

(function(x){
  delete x;
  return x;
})(1);

这里 delete x; 返回false(delete对参数不起作用), 所以x仍是1
Reference/Operators/delete

5.

(function f(f){
 return typeof f();
})(function(){ return 1; });

参数覆盖了f的值, 所以f是参数的函数, 而不是函数本身

14.

with (function(x, undefined){}) length;

length应该是2

(function(){ console.log(arguments.length) })(1,null);
输出 2
(function(){ console.log(arguments.length) })(1,undefined);
输出 2