How do I get random number between -20 and 20 with 3 decimals using JavaScript?

Question

I would liket to use javaScript to generate random number with 3 decimals. using the following code: ${__javaScript((Math.random() * (40) - 20).toFixed(3) * 1,)}

it generate the value -7.829999999999999, but I want the value -7.830.

Anyone knows how do I get what I want? thank you in advance. enter image description hereenter image description here

I tried your code, it seems you are doing it the correct way. You should be getting the output you desire. — Prashanth KR, Mar 09 '18 at 07:39
What you want is apparently a variable that can store the value -7.830 exactly. But this is not possible. In binary, you would need an infinite number of digits to store this number. See [Is floating point math broken?](https://stackoverflow.com/q/588004/1679849) — r3mainer, Mar 09 '18 at 08:34
Possible duplicate of [Is floating point math broken?](https://stackoverflow.com/questions/588004/is-floating-point-math-broken) — Pac0, Mar 16 '19 at 17:08

score 1 · Answer 1 · answered Mar 09 '18 at 07:46

1

Your solution seems to work..

(Math.random() * 40 - 20).toFixed(3) even like this

Working fiddle here : https://jsfiddle.net/ppgcLf6m/2/

answered Mar 09 '18 at 07:46

Aleksandar Djordjevic

98
8

but it generate value -7.829999999999999 actually, which I don't want to get. – Joyce Gao Mar 09 '18 at 08:59
Weird behaviour... Ok, lets try a different approach... 'alert(Math.round((Math.random() * 40 - 20) * 1000) / 1000)' Another working fiddle : https://jsfiddle.net/ppgcLf6m/8/ – Aleksandar Djordjevic Mar 09 '18 at 09:19
tried, but it doesn't work, as it also generate -13.850000000000001 – Joyce Gao Mar 11 '18 at 09:52

score 0 · Answer 2 · answered Mar 09 '18 at 07:43

0

Calling parseFloat on the end result should work.

parseFloat((Math.random() * (40) -20).toFixed(3))

answered Mar 09 '18 at 07:43

Gokul Chandrasekaran

545
3
10

How do I get random number between -20 and 20 with 3 decimals using JavaScript?

2 Answers2