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【ES】笔记-数值扩展

news 2025/6/28 19:05:48

数值扩展

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<body><script>// 0.Number.EPSION 是javaScript 表示的最小精度//EPSILON 属性的值接近于2.22044604925031308088472633361816e-16function equal(a,b){if(Math.abs(a-b)<Number.EPSILON){return true;}else{return false;}}console.log(0.1+0.2===0.3); //打印falseconsole.log(equal(0.1+0.2,0.3)); //打印true//1. 二进制和八进制let b=0b1010;let o=0o777;console.log(b); //打印10console.log(o); //打印511let d=100;let x=0xff;console.log(d); //打印100console.log(x); //打印255//2.Number.isInteger 判断一个数是否为有限数console.log(Number.isFinite(100)); //打印trueconsole.log(Number.isFinite(100/0)); //打印falseconsole.log(Number.isFinite(Infinity)); //打印false//3.Number.isNaN 检测一个数值是否为NaNconsole.log(Number.isNaN(123)); //打印false//4. Number.parseInt Number.parseFloat 字符串转整数console.log(Number.parseInt(5)); //打印5console.log(Number.parseFloat ('3.1415926神奇')); //打印3.1415926//5.Number.isInteger 判断一个数是否为整数console.log(Number.isInteger(5));   //打印trueconsole.log(Number.isInteger(2.5)); //打印false//6.Math.trunc 将数字的小数部分抹掉console.log(Math.trunc(3.5)) //打印3//7.Math.sign 判断一个数到底为正数 负数 还是零console.log(Math.sign(100)); //打印1console.log(Math.sign(-20)); //打印-1console.log(Math.sign(0));   //打印0</script>
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