let arr = ["a","b"]; let obj={ name:'Lucy', age:21, address:'北京', school:'清华大学' } for (a in obj) {//for...in遍历的是Object(包括Array)中的可枚举的属性 console.log("for in:"+a);//1,2 } for (a of obj) {//for ... in语句以任意顺序迭代对象的可枚举属性。 console.log("for of:"+a);//a,b }