Js uses the for loop to traverse the Array

Js uses the for loop to traverse the Array

Today I wrote something boring! For Loop usage! The following code defines array a and array B as a pseudo array!

var a = [1,2,3,0,5,4];var b = document.getElementsByTagName('li'); //[
1
,
2
,
3
,
4
,
5
]

First: incorrect type!

For (var I = 0; I <. length; I ++) {// This writing method is the most basic, but the error is that the array length should not be obtained every time, So we usually use the second Writing Method !}

Type 2: General type!

For (var I = 0, l =. length; I <l; I ++) {// This writing method is the most common, better understood, and also common. For the two types of a and B (pseudo) all arrays are supported .}

Type 3: optimized

For (var I = a. length-1; I> = 0; I --) {// This write method is clever, traversing in reverse order, thus saving a temporary variable! For both a and B (pseudo) arrays. // Google compiler compression will optimize the for loop !}

Fourth: Special settings

For (var I = 0; B [I]; I ++) {// This writing method is not generic, and it won't work for Array! But it is very practical for the collection of dom elements such as array B !}

Fifth: Skill

For (var I = 0, elem; (elem = B [I])! = Null; I ++) {// This method is also used in specific situations. When the element of the array is not equal to a certain value, here, the loop is stopped when null or undefined is encountered, so array a can also be used! // The trick is to assign values while declaring conditions! This reduces the code for assigning temporary variables to a row !}