JavaScript基础语法（运算符）

Dear 丶 2024-03-31 12:54 82阅读 0赞

## JavaScript基础语法（运算符） ##

**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]

### 概述 ###

相比于Java,JS多了一个`===`，其他的下面的运算符都一样。

*  一元运算符：++，–
 *  算术运算符：+，-，\*，/，%
 *  赋值运算符：=，+=，-=…
 *  关系运算符：>，<，>=，<=，!=，==，===…
 *  逻辑运算符：&&，||，!
 *  三元运算符：条件表达式 ? true\_value : false\_value

#### 3.5.1 ==和===区别 ####

**概述:**

*  ==：
    
    1.  判断类型是否一样，如果不一样，则进行类型转换
    2.  再去比较其值
 *  ===：js 中的全等于
    
    1.  判断类型是否一样，如果不一样，直接返回false
    2.  再去比较其值

**代码：**

<!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        
    <script>
        var a1 = 20;
        var a2 = "20";
    
        document.write(a1 == a2);// true 
        document.write(a1 === a2);// false
    </script>
    </body>
    </html>

**运行结果**  
![在这里插入图片描述][40b8c4f4504f465fa3edc9e3402b9f79.png]

[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
[40b8c4f4504f465fa3edc9e3402b9f79.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/03/31/80f050b6bb3745858c6c642ed2a4ef6d.png