JavaScript中遍历数组的方法

for循环

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

for...of

遍历出数组中的每个值

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

for..in

遍历出数组中每个值的下标

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

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

2. 遍历出数组中的每个值　　arr.values()

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

　　　　

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