遍历对象:
1.for..in: 遍历对象key值:
const obj = { id:1,name:'zhangsan',age:18}
for(let key in obj){
console.log(key + '---' + obj[key])
}
2. Object.keys(obj): 返回对象key值数组
console.log(Object.keys(obj)) //['id','name','age']
console.log(Object.values(obj)) //['1','zhangsan','18']