版权声明:本文为博主原创文章,未经博主允许不得转载。 https://blog.csdn.net/u012326462/article/details/82778745
1.传统for循环
var arr=[1,2,3];
for(var i = 0; i < arr.length; i++){
console.log(arr[i]);
}
2. for in 循环
for(var i in arr){
console.log(arr[i]);
}
3. forEach循环 i为数组索引,v索引对应的值
arr.forEach((v,i)=>console.log(i+" "+v));
4. for of 循环
for(var v of arr){
console.log(v);
}
for .. in 与 for .. of区别:for in循环的是键值,不是数组索引。看下面例子
var arr2=[1,2,3,4,5,6];
arr2.value='val';
//在使用for in 遍历时,实际上是对对象属性的循环
for(var i in arr2){
console.log(i+' '+arr2[i]);//这时的i为键值,不为数组索引
}
for(var v of arr2){
console.log(v);
}
输出结果:
0 1
1 2
2 3
3 4
4 5
5 6
value val
1
2
3
4
5
6