function judgeType(obj) {
        if (obj === null) {
          console.log(String(obj));
        } else if (typeof obj === "object") {
          var type = Object.prototype.toString
            .call(obj)
            .replace("[object ", "")
            .replace("]", "")
            .toLowerCase();
          console.log(type);
        } else {
          console.log(typeof obj);
        }
      }

调用judgeType函数

	  judgeType(null); // -> null
      judgeType(undefined); // -> undefined
      judgeType({}); // -> object
      judgeType([]); // -> array
      judgeType(123); // -> number
      judgeType(true); // -> boolean
      judgeType("haha"); // -> string
      judgeType(/123/); // -> regexp
      judgeType(new Date()); // -> date