Restrict Float Precision in JavaScript

Question

I'm working on a function in JavaScript. I take two variables x and y.

I need to divide two variables and display result on the screen:

x=9; y=110;
x/y;

then I'm getting the result as :

0.08181818181818181

I need to do it with using some thing like BigDecimal.js that I found in another post.

I want that result was shown as:

0.081

Solution 1

Try this it is rounding to 3 numbers after coma:

(x/y).toFixed(3);

Now your result will be a string. If you need it to be float just do:

parseFloat((x/y).toFixed(3));

Solution 2

You can do this

Math.round(num * 1000) / 1000

This will round it correctly. If you wish to just truncate rather than actually round, you can use floor() instead of round()

Solution 3

Use this to round 0.818181... to 0.81:

x = 9/110;
Math.floor(x * 1000) / 1000;

Solution 4

Try this

var num = x/y;
parseFloat((Math.round(num * 100) / 100).toPrecision(3))

View more solutions

Comments

[Pointy]

Yes but note that .toFixed() returns a string, not a number. May not matter here of course.

[kajojeq]

Yes, I wonder now how it's matter if: var x = (9/110).toFixed(3); console.log(x); console.log(x*24); console.log(x/45); console.log(x--); all of this works even if it is string. When does it matter? Thanks

[Smern]

@kajojeq, if you are doing like (9/110).toFixed(3) === 0.082 it will return false

[kajojeq]

@smerny Yes you right. I am not often using === and == still gives true. thanks for fast reply!

[Felix Kling]

"When does it matter?" Try x + 42.

[kajojeq]

Right, added line with parsing to float if needed. Hope now It's clear. thanks

[Claies]

You should be aware that this question is a year old, with an accepted answer and multiple possible duplicates. Therefore, you should take extra care to demonstrate how your answer is more useful than the already provided responses.