About array traversal methods of ES5 & ES6

ES5 array traversal methods

 

1, for loop

const arr = [1, 2, 3, 4, 5]

for (let i = 0; i < arr.length; i++) {
  console.log(arr[i])
}

 

2、forEach

const arr = [1, 2, 3, 4, 5]

arr.forEach(function (item) {
  console.log(item)
})

The difference between the for loop: You can not use the break and continue

 

3、every

const arr = [1, 2, 3, 4, 5]

arr.every(function (item) {
  console.log(item)
  return true
})

The distinction for loop: break and can continue, but it must return false, respectively, and return true alternative

 

4、for in

const arr = [1, 2, 3, 4, 5]

for (let index in arr) {
  console.log(arr[index])
}

① for in the design of the object is to be traversed to get a string type of keys, so strictly speaking, does not apply to array traversal

② for in support of break and continue, but in the judgment to use "==" do not use "===", because here is the string index

 

ES6 array traversal methods

 

5、for of

const arr = [1, 2, 3, 4, 5]

for (let item of arr) {
  console.log(item)
}

In addition to the array can traverse, since the object definition structure