chuck
/
es6-11study


			
				
					
						
						
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    <title>Document</title>
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    <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>
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