ES6之数值扩展 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>数值扩展</title>
</head>
<body>
    <script>
        //0. Number.EPSILON 是 JavaScript 表示的最小精度
        //EPSILON 属性的值接近于 2.2204460492503130808472633361816E-16
        function equal(a, b){
            if(Math.abs(a-b) < Number.EPSILON){
                return true;
            }else{
                return false;
            }
        }
        console.log(0.1 + 0.2 === 0.3);
        console.log(equal(0.1 + 0.2, 0.3))

        //1. 二进制和八进制
        let b = 0b1010;
        let o = 0o777;
        let d = 100;
        let x = 0xff;
        console.log(x);

        //2. Number.isFinite  检测一个数值是否为有限数
        console.log(Number.isFinite(100));
        console.log(Number.isFinite(100/0));
        console.log(Number.isFinite(Infinity));
        
        //3. Number.isNaN 检测一个数值是否为 NaN 
        console.log(Number.isNaN(123)); 

        //4. Number.parseInt Number.parseFloat字符串转整数
        console.log(Number.parseInt('5211314love'));
        console.log(Number.parseFloat('3.1415926神奇'));

        //5. Number.isInteger 判断一个数是否为整数
        console.log(Number.isInteger(5));
        console.log(Number.isInteger(2.5));

        //6. Math.trunc 将数字的小数部分抹掉  
          console.log(Math.trunc(3.5));

        //7. Math.sign 判断一个数到底为正数 负数 还是零
        console.log(Math.sign(100));
        console.log(Math.sign(0));
        console.log(Math.sign(-20000));

    </script>
</body>
</html>

 

posted @ 2022-11-20 15:34  安静点--  阅读(22)  评论(0)    收藏  举报