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- <!DOCTYPE html>
- <html lang="en">
- <head>
- <meta charset="UTF-8">
- <meta http-equiv="X-UA-Compatible" content="IE=edge">
- <meta name="viewport" content="width=device-width, initial-scale=1.0">
- <title>Document</title>
- </head>
- <body>
- <script>
- // Number.EPSILON 浮点型计算
- console.log(0.1 + 0.2 === 0.3)
- function equal(a,b){
- return Math.abs(a-b)<Number.EPSILON
- }
- console.log(equal(0.1+0.2,0.3))
- //二进制和八进制
- let b = 0b1010
- let o = 0o777
- let d = 100
- let x = 0xff
- //Number.isFinite 检测一个数值是否为有限数
- //Number.isNaN 检测一个值是否为NaN
- //Number.parseInt 字符串转化数字
- console.log(Number.parseInt('123aaa')) // 123
- console.log(Number.parseFloat('2.3dr')) // 2.3
- // Number.isInteger 判断是否整数
- console.log(Number.isInteger('123')) // false
- //Number.trunc 将小数部分去掉
- //Math.sign 判断一个数是正数、负数、0
- console.log(Math.sign(0)) //0
- console.log(Math.sign(100)) //1
- console.log(Math.sign(-100)) //-1
- </script>
- </body>
- </html>
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