判断js的Array和Object的实现方法

var a = ['hello','world'];
  console.log(typeof a); // object
  console.log(a.toString()); // hello,word 字符串
  console.log(Object.prototype.toString.call(a)); //[object Array]

  var b = {'hello':'world'};
  console.log(typeof b); // object
  console.log(b.toString()); // [object Object]
  console.log(Object.prototype.toString.call(b));// [object Object]

console.log( Array.isArray(a) ); // true
console.log( Array.isArray(b) ); // false