遍历对象的方法

//Object原型链上扩展的方法也会被遍历出来
Object.prototype.fun ()=>{}
var obj = {
  a:1,
  b:2,
  c:3
}
for (const item in obj){
  console.log("属性名："+item+"/属性值："+obj[item]);
}
//属性名：a/属性值：1
//属性名：b/属性值：2
//属性名：C/属性值：3
//属性名：fun/属性值：()=>{}
//而如果我们不希望搜索到原型上的，我们就可以使用hasOwnProperty
for (const item in obj){
  if (obj.hasOwnProperty(item)){
    console.log("属性名："+item+"/属性值："+obj[item]);
  }
}
//属性名：a/属性值：1
//属性名：b/属性值：2
//属性名：c/属性值：3

//注意：当属性名为数字的时候会排序，key/values/entries都有这个特性~
const anobj={100:'a',2:'b',7:'c'};
console.log(Object.keys(anobj));//console:['2',7,'100']
const str = 'hello';
console.log(Object.keys(str));//["0","1","2","3","4"]
const arr = ['a','b','c'];
console.log(Object.keys(arr));//["0","1","2"]
var obj = {a:1,b:2,c:3};
console.log(Object.keys(obj));//["a","b","c"]

//注意：当属性名为数字的时候会排序，key/values/entries都有这个特性~
//注意：当属性名为数字的时候会排序，key/values/entries都有这个特性~
const obj1={100:1,d:2,a:9,1:3,5:99,b:8};
console.log(Object.values(obj1));//[3,99,1,2,9,8]
const str='hello';
console.log(Object.values(str));//["h","e","""""o"]
const arr=['a','b','c'];
console.log(Object.values(arr));//["a","b","c"]
var obj2={a:1,b:2,c:3};
console.log(Object.values(obj2));//["1","2","3"]v

//注意：当属性名为数字的时候会排序，key/values/entries都有这个特性~
const obj1={100:1,d:2,a:9,1:3,5:99,b:8};
console.log(Object.entries(obj1));//[["1",3],["5",99],["100",1],["d",2],["a",9],["b",8]]
const str='hello';
console.log(Object.entries(str));//[["0","h"],["1","e"],["2",""],["3",""],["4","o"]]
const obj2={a:1,b:2,c:3};
console.log(Object.entries(obj2));//[["a",1],["b",2],["c",3]]
const obj3={a:1,b:2,c:3};
for (const [key,value] of Object.entries(obj3)){
  console.log(`${key}:${value}`);
}
//a:1
//b:2
//c:3

//注意：当属性名为数字的时候会排序，key/values/entries都有这个特性
const arobj={100:1,d:2,a:9,1:3,5:99,b:8};
console.log(Object.getOwnPropertyNames(arobj));//["1","5","100","d","a","b"]
const str='hello';
console.log(Object.getOwnPropertyNames(str));//["0","1","2","3","4","length"]
const arr=['a','b','c'];
console.log(Object.getOwnPropertyNames(arr));//s["0","1","2","length"]
const obj={a:1,b:2,c:3};
console.log(Object.getOwnPropertyNames(obj));//["a","b","c"]
const syobj ={a:1,b:2 }
const symbol1=Symbol('symbol1')
const symbol2=Symbol('symbol2')
syobj[symbol1]='hello'
syobj[symbol2]='world'
console.log(Object.getOwnPropertyNames(syobj));//["a","b"]

const obj={a:1,b:2,c:3};
const symbol1=Symbol('symbol1')
const symbol2=Symbol('symbo12')
obj[symbol1]='hello'
obj[symbol2]='world'
console.log(Object.getOwnPropertySymbols(obj));//[Symbol(symbol1),Symbol(symbol2)]

const obj={a:1,b:2,c:3};
const symbol1=Symbol('symbol1')
const symbol2=Symbol('symbol2')
obj[symbol1]='hello'
obj[symbol2]='world'
console.log(Reflect.ownKeys(obj));//["a","b","c",Symbol(symbol1),Symbol(symbol2)