JS for while loop

This time I will bring you the for while loop of JS, what are the precautions for using the for while loop of JS, the following is a practical case, let's take a look.

Loop statement:

For

##　for loop format

for（var i = 0; i  <p style="text-align: left;"><img src="/static/imghwm/default1.png" data-src="https://img.php.cn/upload/article/000/061/021/7c67b9be37e1465ab2d640c04040b193-0.png?x-oss-process=image/resize,p_40" class="lazy" alt=""></p> <p   style="max-width:90%">For loop execution sequence: <span style="color: #3366ff"></span></p> Enter ② Judgment... Loop<p style="text-align: left;"></p> If the judgment is false, end<p style="text-align: left;"></p><p style="text-align: left;">while<span style="color: #ff0000"></span></p>　<p style="text-align: left;"><span style="color: #3366ff">while loop<a href="http://www.php.cn/code/5908.html" target="_blank">Format</a></span></p><pre class="brush:php;toolbar:false">var i = 0;
while（i  If ibreak ends all loops<p style="text-align: left;"></p>continue skips this loop and will execute the following. <p style="text-align: left;"></p><p style="text-align: left;"><img src="/static/imghwm/default1.png" data-src="https://img.php.cn/upload/article/000/061/021/7c67b9be37e1465ab2d640c04040b193-1.gif?x-oss-process=image/resize,p_40" class="lazy" id="code_img_closed_6592d1c9-6f92-448f-9146-02a322a53731" alt=""><img src="/static/imghwm/default1.png" data-src="https://img.php.cn/upload/article/000/061/021/7c67b9be37e1465ab2d640c04040b193-2.gif?x-oss-process=image/resize,p_40" class="lazy" id="code_img_opened_6592d1c9-6f92-448f-9146-02a322a53731" alt=""></p><pre class="brush:php;toolbar:false">for（）{
     If（i ==2）{
        Continue;
    }                            
}

View Code

will skip the case of i=2, end i=1 and then execute i=3.

The difference between for and while

To determine the number of times, use for

While while terminates the loop until a certain condition is met. (Looking for books in the library, I don’t know how many books)

Variable classification:

1. Global variables are also called external variables, which are variables defined outside the function. It does not belong to a function, it belongs to a source program file. Its scope is the entire source program.

2. Local variables In a program, variables that can only be accessed in a specific procedure or function are relative to global variables

Scope:

The scope of the variable Only within defined curly braces.

Short circuit:

Only performs one operation, high efficiency

Other content:

　

Typeof

DetermineData type There is a return value                                           # (Can you assign a value to a variable?) Var num = 1+2 && 3+4 Output 3 is judged to be true because both sides are true

　0 false　Not 0 true

Empty false

Non-empty true

##Notes

：

Homework questions:

Control statementNote the format

if(判断){
    alert();
}else{
    alert();
}

if语句格式

　　　　变量要在开头定义。

　　　　重复的代码要优化重构。

相信看了本文案例你已经掌握了方法，更多精彩请关注php中文网其它相关文章！

推荐阅读：

max-width和min-width的使用技巧

android textinput显示不全怎么解决

The above is the detailed content of JS for while loop. For more information, please follow other related articles on the PHP Chinese website!