math.ceil 上舍入 Math.floor 下舍入

math.ceil 上舍入 Math.floor 下舍入

var x = 99.2000;

var y = 2;

var z= -90.1;

console.log(Math.ceil(x));

console.log(Math.floor(x));

console.log(Math.ceil(z));

console.log(Math.floor(z));

输出100 99 -90 -91