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- <!DOCTYPE html>
- <html lang="en">
- <head>
- <meta charset="UTF-8">
- <meta name="viewport" content="width=device-width, initial-scale=1.0">
- <title>Document</title>
- </head>
- <body>
- <!--
- 运算符: + - * / %(取余/取模)
- -->
- <script>
- var a = 1;
- var b = 10;
- var c = 5;
- var d = 21;
- // 加法
- console.log(a + 3);//4 number + number 加法运算
- console.log(a + '90'); //190 number + string 拼接
- console.log(a + true); //2 number + boolean 正常运算
- console.log(a + undefined);//NaN 非法数字
- console.log(a + null);// 1 number+null => number
- // 减法
- console.log(b - 3);//7 number - number 减法运算
- console.log('90' - b); //80 number - string 正常减法运算
- console.log(b - true); //9 number - boolean 正常运算
- console.log(b - undefined);//NaN 非法数字
- console.log(b - null);//10 number-null => number
- // 乘法
- console.log(c * 3);//15 number * number 乘法运算
- console.log('9' * c); //45 number * string 正常运算
- console.log(c * true); //5 number * boolean 正常运算
- console.log(c * undefined);//NaN 非法数字
- console.log(c * null);//0 number*null => 0
- // 除法
- console.log(d / 3);//7 number * number 除法运算
- console.log(d / '3'); //7 number * string 正常运算
- console.log(d / false); //Infinity number * boolean 正常运算
- console.log(d / undefined);//NaN 非法数字
- console.log(d / null);//Infinity number*null => Infinity
- // ！important > 内联 > id ...
- // +infinity 1000 100
- </script>
- </body>
- </html>
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