var person={ name:"ai", age:"22"};
for (var n in person){ console.log(n); console.log(typeof n); console.log(person.n);//常会思路是错的,这样他会找person.n即n这个属性,person中并不存在 console.log(person[n]);//上面那样是找常量,用中括号会找变量}