1.使用for-in的方式

let obj = {
    name:'lebron',
    age:35,
    sex:'man'
}
for(let i in obj){
    console.log(`${i}:${obj[i]}`)
}

2.使用Object.keys()和Object.values()

let obj = {
    name:'lebron',
    age:35,
    sex:'man'
}
let arr = Object.keys(obj).map(e =>{
    return `${e}:${obj[e]}`
})
console.log(arr) 
//["name:lebron", "age:35", "sex:man"]

3.Object.keys(),Object.values(),Object.entries的区别

1. 遍历key：Object.keys()
2. 遍历值：Object.values()
3. 遍历Key和值：Object.entries

let obj = {
    name:'lebron',
    age:35,
    sex:'man'
}
let keys = Object.keys(obj);
let val = Object.values(obj);
let entries = Object.entries(obj);
console.log(keys)
//["name", "age", "sex"]
console.log(val)
//["lebron", 35, "man"]
console.log(entries)
//[["name", "lebron"],["age", 35],["sex", "man"]]

4.如何判断一个对象是否为空

Object.keys(obj).length，通过对象的可枚举属性的个数来判断