jilingxf

js的运算符学习笔记

js的运算符

image


1、加号运算

<!DOCTYPE html>
<html lange = "en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <h1>js运算</h1>
    <h2>加号运算</h2>
    <script type="text/javascript">
        var a = 1 + 1 + "a" + ( 1 + 2 );
        document.write(a);

    </script>




</body>

运行结果为：注意运算顺序

image

减号运算和称号运算  略

除号运算

<!DOCTYPE html>
<html lange = "en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <h1>js运算</h1>
    <h2>加号运算</h2>
    <script type="text/javascript">
        var a = 1 + 1 + "a" + ( 1 + 2 );
        document.write(a);

    </script>

    <h2>除号运算</h2>
    <a>     1/0 是无穷 a = 1 / 0 =
    <script type="text/javascript">
        var a = 1 / 0;
        document.write(a);

    </script>

    </a>

    <br/>
    <a>     0/0 得到的不是数 a = 10 / 0 =
    <script type="text/javascript">
        var a = 0 / 0;
        document.write(a);
    </script>

    </a>

</body>


结果为

image


取余运算 %（略）


++  -- 

<!DOCTYPE html>
<html lange = "en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
    <h1>js运算</h1>
    <h2>加号运算</h2>
    <script type="text/javascript">
        var a = 1 + 1 + "a" + ( 1 + 2 );
        document.write(a);

    </script>

    <h2>除号运算</h2>
    <a>     1/0 是无穷 a = 1 / 0 =
    <script type="text/javascript">
        var a = 1 / 0;
        document.write(a);

    </script>

    </a>

    <br/>
    <a>     0/0 得到的不是数 a = 10 / 0 =
    <script type="text/javascript">
        var a = 0 / 0;
        document.write(a);
    </script>

    </a>

    <br/>
    <a>      b = a++ 
    <script type="text/javascript">
        var a = 10;
        b = a++
        document.write("a = " + a + " b = " + b);
    </script>

    </a>
    <br/>
    <a>     b = ++a    
    <script type="text/javascript">
        var a = 10;
        b = ++a
        document.write("a = "  + a + " b = " + b);
    </script>

    </a>
</body>

赋值运算  从右向左  ，计算顺序  从左至右

image


a+=10  等同于 a+=10

a += 10 +1 为 a+10

结果为21

posted on 2020-10-15 14:56  jilingxf  阅读(148)  评论(0)    收藏  举报

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