JavaScript rounding to two digits does not always work

Question

I have a incremental control in the UI that increase/decrease values by clicking left and right arrows. See the UI Image:

I'm trying to round a float returned by UI to two decimal points. It works most of the times but I get raw values once in a while. Here is the sample code"

input = document.getElementById("in");
input.addEventListener("input", function() {
    console.log(input.value + " rounded : " + Math.round((input.value  - 0.01) * 100) / 100);
});

<input id="in" type="number"></input>

Any thoughts?

https://stackoverflow.com/questions/588004/is-floating-point-math-broken — epascarello, Apr 23 '21 at 22:34
You should at very least include values in your question taht are throwing an error or that are not giving you the expected outcome you desire. — dale landry, Apr 23 '21 at 22:43
Does this answer your question? [How to round to at most 2 decimal places, if necessary?](https://stackoverflow.com/questions/11832914/how-to-round-to-at-most-2-decimal-places-if-necessary). You want the second answer, not the accepted one. — SuperStormer, Apr 23 '21 at 22:46

score 0 · Answer 1 · answered Apr 23 '21 at 22:44

0

that's just how it goes with floats and computers, sometimes it just slightly misses.

use .toFixed(2) to round to 2 decimal places.

answered Apr 23 '21 at 22:44

Matthew S.

43
5

JavaScript rounding to two digits does not always work

1 Answers1