Math()方法

1. Math.radom()生成 [0,1) 的随机数 ```javascript let num = Math.random()

//返回[0,9)的随机数 let num = parseInt(Math.random() * 9)

//返回[1,10]的随机数 let num = parseInt(Math.random() * 10) + 1

2. 舍入
   1. 向上取整
```javascript
    let num = Math.ceil(1.4);
    console.log(num);
//2

1. 向下取整

   let num = Math.floor(1.4);
   console.log(num);
   //1

2. 标准四舍五入

   let num = Math.round(1.4)
   console.log(num);
   //1
   let num = Math.round(1.5)
   console.log(num);
   //2

1. 次方

    let num = Math.pow(2, 2)
    console.log(num);
   //4

2. 绝对值

    let num = Math.abs(-2)
    console.log(num);
   //2

3. 平方根

    let num = Math.sqrt(4)
    console.log(num);
   //2

4. 最大值

    let num = Math.max(1, 2, 3, 10, 100, 300)
    console.log(num);
   //300

5. 最小值

    let num = Math.min(1, 2, 3, 10, 100, 300)
    console.log(num);
   //1