JavaScript基础语法（流程控制语句）

约定不等于承诺〃 2024-03-31 12:56 86阅读 0赞

## JavaScript基础语法（流程控制语句） ##

**学习路线**：[JavaScript基础语法（输出语句）][JavaScript]\->[JavaScript基础语法（变量）][JavaScript 1]\->[JavaScript基础语法（数据类型）][JavaScript 2]\->[JavaScript基础语法（运算符）][JavaScript 3]\->[JavaScript基础语法（流程控制语句）][JavaScript 4]\->[JavaScript基础语法（类型转换）][JavaScript 5]\->[JavaScript基础语法（函数）][JavaScript 6]\->[Array\_JavaScript][Array_JavaScript]\->[String\_JavaScript][String_JavaScript]\->[自定义对象\_JavaScript][JavaScript 7]\->[JavaScript\_BOM][JavaScript_BOM]\->[Window对象][Window]\->[confirm()、setInterval()、setTimeout()][confirm_setInterval_setTimeout]\->[History、Location][History_Location]\->[闪烁的灯泡][Link 1]\->[JavaScript\_DOM][JavaScript_DOM]\->[事件绑定(onclick,onfocus,onblur)][onclick_onfocus_onblur]\->  
[事件绑定(onmouseout,onmouseover)  
][onmouseout_onmouseover_]\->[事件绑定(onsubmit)表单提交  
][onsubmit_]\->[提交表单与验证表单案例  
][Link 2]

**简介**：JavaScript 中提供了和 Java 一样的流程控制语句，如下

### if 语句 ###

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        
    <script>
        var cnt = 3;
        if (cnt == 3) {
        
            document.write(count);
        }
    </script>
    </body>
    </html>

### switch 语句 ###

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
    <script>    
    var num = 3;
    switch (num) {
        
        case 1:
            alert("星期一");
            break;
        case 2:
            alert("星期二");
            break;
        case 3:
            alert("星期三");
            break;
        case 4:
            alert("星期四");
            break;
        case 5:
            alert("星期五");
            break;
        case 6:
            alert("星期六");
            break;
        case 7:
            alert("星期日");
            break;
        default:
            alert("输入的星期有误");
            break;
    }
    </script>
    </body>
    </html>

### for 循环语句 ###

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        
    <script>
        var str = "abc"
        for(var i = 0; i < str.length; ++ i){
        
            console.log(str.charAt(i))
        }
    </script>
    </body>
    </html>

### while 循环语句 ###

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        
    <script>
        var sum = 0;
        var i = 1;
        while (i <= 100) 
        {
        
            sum += i;
            i++;
        }    
    </script>
    </body>
    </html>

### dowhile 循环语句 ###

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        
    <script>
        var sum = 0;
        var i = 1;
        do {
        
            sum += i;
            i++;
        }
        while (i <= 100);  
    </script>
    </body>
    </html>

[JavaScript]: https://blog.csdn.net/qq_51447496/article/details/128085137
[JavaScript 1]: https://blog.csdn.net/qq_51447496/article/details/128085348
[JavaScript 2]: https://blog.csdn.net/qq_51447496/article/details/128086148
[JavaScript 3]: https://blog.csdn.net/qq_51447496/article/details/128086681
[JavaScript 4]: https://blog.csdn.net/qq_51447496/article/details/128088817
[JavaScript 5]: https://blog.csdn.net/qq_51447496/article/details/128087248
[JavaScript 6]: https://blog.csdn.net/qq_51447496/article/details/128088986
[Array_JavaScript]: https://blog.csdn.net/qq_51447496/article/details/128089474
[String_JavaScript]: https://blog.csdn.net/qq_51447496/article/details/128089631
[JavaScript 7]: https://blog.csdn.net/qq_51447496/article/details/128089766
[JavaScript_BOM]: https://editor.csdn.net/md/?articleId=128095193
[Window]: https://blog.csdn.net/qq_51447496/article/details/128095300
[confirm_setInterval_setTimeout]: https://blog.csdn.net/qq_51447496/article/details/128103458
[History_Location]: https://blog.csdn.net/qq_51447496/article/details/128104240
[Link 1]: https://blog.csdn.net/qq_51447496/article/details/128095524
[JavaScript_DOM]: https://blog.csdn.net/qq_51447496/article/details/128104720
[onclick_onfocus_onblur]: https://blog.csdn.net/qq_51447496/article/details/128110532
[onmouseout_onmouseover_]: https://blog.csdn.net/qq_51447496/article/details/128112439
[onsubmit_]: https://blog.csdn.net/qq_51447496/article/details/128112553
[Link 2]: https://blog.csdn.net/qq_51447496/article/details/128112770