5.21 Math常用的方法

<script>
 Math.isOdd = val => val %2 !==0
 Math.isEven = val => val %2 !==0
 Math.rnd=(max,min = 0) =>{
     return Math.round(Math.random()*(max - min))+min
 }
 console.log(Math.floor(3.1)); //向下取整
 console.log(Math.ceil(3.1)); //向上取整
 console.log(Math.round(3.1)); //四舍五入
 console.log(Math.round(3.5));
 console.log(Math.abs(-3));
 console.log(Math.pow(2,3));
 console.log(Math.max(2,3,20,50));
 console.log(Math.min(2,3,20,50));
 console.log(Math.rnd(30,20));
 console.log(Math.isEven(22));
 console.log(Math.isOdd(23));
 console.log(Math.isOdd(21));
</script>