console.log("forEach========");
obj.forEach((item,idx)=>{
console.log(item,idx);});
console.log("for-in========");for(let index in obj){
console.log(index,obj[index]);}
console.log("for-of========");for(let item of obj){
console.log(item,s[item]);}//结果
forEach========//报错for-in========
a 1
b 2
c 3
d 4for-of========//报错
测试数组
console.log("forEach========");
arr.forEach((item,idx)=>{
console.log(item,idx);});
console.log("for-in========");for(let index in arr){
console.log(index,arr[index]);}
console.log("for-of========");for(let item of arr){
console.log(item,arr[item]);}//结果
forEach========304152for-in========031425
name 22
d 66for-of========3 undefined
4 undefined
5 undefined
测试Set
console.log("forEach========");
s.forEach((item,idx)=>{
console.log(item,idx);});
console.log("for-in========");for(let index in s){
console.log(index,s[index]);}
console.log("for-of========");for(let item of s){
console.log(item,s[item]);}//结果
forEach========1122{ b:3}{ b:3}for-in========
d 4for-of========1 undefined
2 undefined
{ b:3} undefined
测试Map
console.log("forEach========");
m.forEach((item,idx)=>{
console.log(item,idx);});
console.log("for-in========");for(let index in m){
console.log(index,m[index]);}
console.log("for-of========");for(let item of m){
console.log(item,m[item]);}//结果
forEach========3{ a:4}435'4'for-in========
d 4for-of========[{ a:4},3] undefined
[3,4] undefined
['4',5] undefined