1.取绝对值 //100
var value = Math.abs(-100);
console.log(value);
2.向上取整 //2
var value = Math.ceil(1.2);
console.log(value);
3.向下取整 // 1
var value = Math.floor(1.8);
console.log(value);
4.最大值 // 67
var value = Math.max(23,34,5,67,8);
console.log(value);
5.最小值//5
var value = Math.min(23,34,5,67,8);
console.log(value);
. 四舍五入//1
var value = Math.round(1.3);
console.log(value);
7，随机数
0-1包括0
但不包括1
var value = Math,random();
console.log(value);
