Simple decimal arithmetic for the browser and node.js!
Why don't my numbers, like 0.1 + 0.2 add up to a nice round 0.3, and instead I get a weird result like 0.30000000000000004? Because internally, computers use a format (binary floating-point) that cannot accurately represent a number like 0.1, 0.2 or 0.3 at all. Source : http://floating-point-gui.de/
I wrote this because I needed to do simple computation in the browser and I couldn't find a lightweight library to do it.
<script src="lib/decimal.js"></script>npm install decimalthen in your program
let Decimal = require('decimal');// Regular JavaScript >>> 0.1 + 0.2 0.30000000000000004 // Using Decimal.js >>> Decimal('0.1').add('0.2').toString() '0.3' // Static method >>> Decimal.add('0.1', '0.2').toString() '0.3'// Regular JavaScript >>> 0.3 - 0.1 0.19999999999999998 // Using Decimal.js >>> Decimal('0.3').sub('0.1').toString() '0.2' // Static method >>> Decimal.sub('0.3', '0.1').toString() '0.2'// Regular JavaScript >>> 4.01 * 2.01 8.060099999999998 // Using Decimal.js >>> Decimal('4.01').mul('2.01').toString() '8.0601' // Static method >>> Decimal.mul('4.01', '2.01').toString() '8.0601'// Regular JavaScript >>> 1.21 / 0.1 12.100000000000001 // Using Decimal.js >>> Decimal('1.21').div('0.1').toString() '12.1' // Static method >>> Decimal.div('1.21', '0.1').toString() '12.1' // Division by zero >>> Decimal('1.21').div('0').toString() node:internal/modules/run_main:122 triggerUncaughtException(...) ^ [DivisionByZeroError: Division by zero]Of course you can, I suck at math, and this implementation is very naive. If you are a math Guru and you see something wrong or a way to simplify things you can send in a pull request.
Create a new Decimal from n. n can be a string, integer, or another Decimal.
Returns the Decimal instance as a string.
>>> Decimal('123.456').toString() '123.456'Turn a Decimal into a Number.
>>> Decimal('123.456').toNumber() 123.456Return a new Decimal containing the instance value plus n.
>>> Decimal('0.1').add('0.2').toString() '0.3'Return a new Decimal containing the instance value minus n.
>>> Decimal('0.3').sub('0.1').toString() '0.2'Return a new Decimal containing the instance value multiplied by n.
>>> Decimal('4.01').mul('2.01').toString() '8.0601'Return a new Decimal containing the instance value integrally divided by n.
>>> Decimal('1.21').div('0.1').toString() '12.1'Returns a new Decimal containing the absolute value.
>>> Decimal('-123.456').abs().toString() '123.456'Returns a new Decimal rounded down to the nearest integer.
>>> Decimal('123.456').floor().toString() '123' >>> Decimal('-123.456').floor().toString() '-124'Returns a new Decimal rounded up to the nearest integer.
>>> Decimal('123.456').ceil().toString() '124' >>> Decimal('-123.456').ceil().toString() '-123'Returns a string representation of the decimal with a fixed number of decimal places. Rounds the last decimal place.
>>> Decimal('123.456').toFixed('2') '123.46' >>> Decimal('123').toFixed('2') '123.00'All instance methods are also available as static methods:
>>> Decimal.add('1.1', '2.2').toString() '3.3' >>> Decimal.abs('-123.456').toString() '123.456'