JS遍历对象

1 Object.keys

var list = {a:123,b:456,c:789}
Object.keys(list).forEach(item => console.log(item))
//a
//b
//b
Object.keys(list).forEach(item => console.log(list[item]))
//123
//456
//789

2 for in

for (let key in list ) {
    console.log(key)
}
//a
//b
//c

3 Object.getOwnPropertyNames

4 Object.getOwnPropertySymbols