獲取對象長度
var????obj = {"a1":1,"a2":2};
var????arr = Object.keys(obj);? ? // arr = ["a1","a2"];
var????len = arr.length;
console.log(len);????//結果為2
獲取對象長度
var????obj = {"a1":1,"a2":2};
var????arr = Object.keys(obj);? ? // arr = ["a1","a2"];
var????len = arr.length;
console.log(len);????//結果為2