Metic

Easy math decimals for JS

metic.add(0.1, 0.2, 2) === 0.3

This is a simple and useful package to help you on arithmetics.

Context

If you've ever tried to sum decimal numbers in JavaScript, you were definitely surprised...

We know that 0.1 + 0.1 is, as you expect, 0.2.

But sometimes you get some unexpected result.

As for 0.1 + 0.2.

The result is not 0.3 as you would expect, but it is 0.30000000000000004.

Yes, the first time I was surprised too. However, if you search further to find out what happens via these links:

• Why 0.1 + 0.2 == 0.3 is false in JS?
• Why 0.1 + 0.2 ≠ 0.3 in JavaScript

Install

npm install metic

Usage

import metic from 'metic'
// import {metic} from 'metic'

metic.add(0.1, 0.2) // => 0.3

You can also use as many decimals places as you like and ensure the value will be as close to what you expect.

import metic from 'metic'
// import {metic} from 'metic'

/**
 * Calculate the sum of two decimals properly.
 * @param {number} a - First value to be considered in the sum.
 * @param {number} b - Second value to be considered in the sum.
 * @param {number} positions - Number of decimals we expect as our result.
 */
metic.add(0.1, 0.222, 3) // => 0.322

LICENSE

MIT