js中数组遍历的几种方式

1、for循环

var arr = [2, 3, 12, 34, 56, 123, 56]
for (i = 0; i < arr.length; i++) {
    console.log(arr[i]);
}

2、foreach循环

var arr = [2, 3, 12, 34, 56, 123, 56]
arr.forEach(function(ele,index) {
     console.log(ele);
})

3、for in 循环

var arr = [2, 3, 12, 34, 56, 123, 56]
for(j of arr) {
    console.log(j);
}

4、for of循环(需要ES6支持)

var arr = [2, 3, 12, 34, 56, 123, 56]
for (let value of arr) {
    console.log(value)
};

5、map遍历

var arr = [2, 3, 12, 34, 56, 123, 56]
arr.map(function(n) {
     console.log(n)
})