JavaScript中遍历数组的方法

Posted 2021-03-16 lotus3904

for循环

1 let arr=["A","B","C","D","E","F"];
2 for(let i=0;i<arr.length;i++){
3    console.log(arr[i]);
4 }

for...of

遍历出数组中的每个值

1 let arr=["A","B","C","D","E","F"];
2 for(let item of arr){
3     console.log(item); 
4 }
//A B C D E F

for..in

遍历出数组中每个值的下标

1 let arr=["A","B","D","E","F"];
2 for(let item in arr){
3     console.log(item); 
4 }
//0 1 2 3 4 5

ES6新增for...of的用法

1. 遍历出数组中每个值的键（下标）　　arr.keys()

   1 let arr=["A","B","C","D","E","F"];
   2 for(let item of arr.keys()){
   3     console.log(item); 
   4 }
   5 //0 1 2 3 4 5

    

2. 遍历出数组中的每个值　　arr.values()

   1 let arr=["A","B","C","D","E","F"];
   2 for(let item of arr.values()){
   3     console.log(item); 
   4 }
   5 //A  B C D E F

    

3. 遍历出数组中的每个值，以及每个值对应的下标　　arr.entries()

　　　　

 1 let arr=["A","B","C","D","E","F"];
 2 for(let item of arr.entries()){
 3     console.log(item); 
 4 }
 5 /**
 6 [ 0, ‘A‘ ]
 7 [ 1, ‘B‘ ]
 8 [ 2, ‘C‘ ]
 9 [ 3, ‘D‘ ]
10 [ 4, ‘E‘ ]
11 [ 5, ‘F‘ ]
12 **/