schowdhuri / round-half-even

Banker's rounding utility

Round Half to Even

A utility for tie-breaking rounding, also called Banker's Rounding or Commercial Rounding.

Read more: https://en.wikipedia.org/wiki/Rounding#Round_half_to_even

Demo

https://rawgit.com/schowdhuri/round-half-even/master/demo/index.html

Installation

Using npm:

npm install --save round-half-even

Or yarn:

yarn add round-half-even

Usage

roundHalfEven(floatingPointValue, numberOfDecimals);

Node.js

import roundHalfEven from "round-half-even";
roundHalfEven(1.435, 2); // returns 1.44

Within the browser:

<script src="https://unpkg.com/round-half-even"></script>
<script>
  roundHalfEven(1.435, 2); // returns 1.44
</script>

Development

Make changes to src/index.js. Generate the browser-ready package:

npm run build

or

yarn build

Run tests:

npm test

or

yarn test

MIT Licensed

round-half-even's Issues

Unable to handle exponential notational numbers

in index.js:

round-half-even/src/index.js

Line 25 in 1b6d954

const strNum = `${value}`.replace(/0+$/, "");

If an exponential number is passed e.g. 1e-8, the strNum will be "1e-8", which does not have a decimal and subsequently is unable to be rounded.

roundHalfEven(1e-8, 2);        // expected: 0.00, actual: 1e-8
roundHalfEven(0.000000010, 2); // expected: 0.00, actual: 1e-8

Might want to consider doing a value.toFixed(20) in there, to coerce it into decimal notation. On second thought this will pre-round the value and most likely not work as intended.

numberOfDecimals not working correctly

roundHalfEven(-104.8936316, 7) // returns: -104.89
roundHalfEven(-83.0715644, 7) // returns: -83.07

I expected the same number as return value.

not consider numDecimals = 0