修改楼层/天花板功能以使用1以外的数字？

Question

By default the floor function always rounds down and the ceil function always rounds up to the nearest '1'

How would I round down/up to the nearest 20, or the nearest 1,000?

Say I had a number x and a factor y.

I want to find the closest factor of y to x.

I am using this to find maximum and minimum values for a graph. Thanks.

Answer 1

简单：

var z = y * Math.floor(x / y);

Answer 2

Math.floor(x / 20) * 20;
Math.ceil(x / 20) * 20;

In your case:

Math.floor(x / y) * y;

The x / y turns the expression into units of y ; with .floor() or .ceil() you then round it down or up; afterwards you multiply with y again to get your final answer.