Math

1，向下取整

<script>
    //向下取整
    function fun1(num){
        return Math.floor(num);
    }
    console.log("29.1向下取整为："+fun1(29.1));//向下取整为29
    console.log("-29.1向下取整为："+fun1(-29.1));//向下取整为-28
</script>

2，获取两个整数之间的随机整数，并且包含这两个整数

<script>    
    //获取两个整数之间的随机整数，并且包含这两个整数
    function fun2(min,max){
        return Math.floor(Math.random()*(max-min+1))+min;
    }
    console.log("7~50之间的随机整数为："+fun2(7,50));
</script>

3，随机点名

<script>
    //随机点名
    var arr=["曾凡良","曾志攀","吕布","刘鸿伟","赖海峰"];
    var n=fun2(0,arr.length);//获取随机索引
    console.log("被点到名字的同学是："+arr[n]);//根据随机索引找打数组元素
</script>