Object.keys()、Object.values()、Object.entries()用法总结

            let person={
                name:'一只流浪的kk',
                age:20,
                eat:function(){}
            }
            console.log(Object.keys(person));//    ['name','age','eat']

 let arr=[1,2,3,4,5];
 console.log(Object.keys(arr));//['0','1','2','3','4','5']

let str='hello';
console.log(Object.keys(str));//['0','1','2','3','4']

 let person={
                   name:'一只流浪的kk',
                   age:18,
                   eat:function(){
                       
                   }
           }
           Object.keys(person).map((key)=>{
                   person[key];//获得属性对应的值，可以进行其它处理
           })

let obj = {
    foo : "bar",
    baz : 20
};
console.log(Object.values(obj));  // ["bar", 20]

const obj = {100 : "a", 2 : "b", 7 : "c"};
console.log(Object.values(obj));   //["b", "c", "a"]

const obj = Object.create({},{p : {value : 10}});
console.log(Object.values(obj));    
console.log(Object.getOwnPropertyDescriptors(obj)); // []

const obj = Object.create({},{p:{
     value : 10,
     enumerable : true,
     configurable : true,
     writable : true,
}})
console.log(Object.values(obj));    //[10]

//如果Object.values方法的参数是一个字符串，会返回各个字符组成的一个数组。
Object.values({ [Symbol()]: 123, foo: 'abc' });
console.log(Object.values('foo'));  //["f", "o", "o"]

console.log(Object.values(42));  // []
console.log(Object.values(true));  // []
console.log(Object.values(undefined));   //error
console.log(Object.values(null));   //error

var obj = { foo: 'bar', baz: 42 };
console.log(Object.entries(obj));

console.log(Object.entries({ [Symbol()]: 123, foo: 'abc' }));  // [ [ 'foo', 'abc' ] ]

let obj = {
    one : 1,
    two : 2,
}
for(let [k , v] of Object.entries(obj)){
     console.log(`${JSON.stringify(k)} : ${JSON.stringify(v)}`);
}

const obj = {foo : "bar", baz : 10};
const map = new Map(Object.entries(obj));
console.log(map); 

const entries = (obj) => {
     let result = [];
     const objType = typeof(obj);
     if(obj === undefined || obj === null){
          throw new TypeError();
     }
     if(objType === "number" || objType === "boolean"){
         return [];
     }
     for(let k of Object.keys(obj)){
         result.push([k,obj[k]]);
     }
     return result
}