hyoka

hyoka is a simple math expression parser and evaluator for JavaScript and TypeScript. it uses decimal.js to ensure precision of floating point calculations.

Features

Supports implicit multiplication and parenthesis grouping
Binary and unary operators are supported
Supports mathematical functions
Precision and rounding mode can be configured

Installation

This library can be used in both node.js and in the browser.

Using npm:

npm install hyoka

Using yarn:

yarn add hyoka

in the browser:

<script src="https://cdn.jsdelivr.net/npm/hyoka@latest/dist/umd/hyoka.js"></script>

<script src="https://cdn.jsdelivr.net/npm/hyoka@latest/dist/esm/hyoka.mjs" type="module"></script>

Usage

// using ES6 import
import {Expression} from 'hyoka';
// or using require
const { Expression } = require('hyoka');

new Expression('0.1 + 0.2').evaluate(); // 0.3
new Expression('2 * 6 / 3').evaluate(); // 4

// using unary prefix operators
new Expression('- 1 + 2').evaluate(); // 1
new Expression('+ 1 - - 2').evaluate(); // 3

// implicit multiplication
new Expression('2(6 / 3)').evaluate(); // 4

//Trig Functions
new Expression('sin(π)').evaluate(); // 0
new Expression('cos(pi / 2)').evaluate(); // -0.5

// Even more complex expressions
new Expression('2(4(6 / 3 + 2) + 2^3 / - 2(2.5!))').evaluate(); //5.413192236417259652

Configuration

hyoka configuration extends that of decimal.js. this means that all configuration options of decimal.js are available. the following configuration options are available:

precision: the number of digits of precision to use
rounding: the rounding mode to use
modulo: the modulo to use
toExpNeg: the exponent of 10 to use for negative zero
toExpPos: the exponent of 10 to use for positive zero
minE: the minimum exponent value
maxE: the maximum exponent value
crypto: whether to use the crypto module for random number generation
angles: the unit of angles to use for trig functions
decimalPlaces: the number of decimal places of returned value

The config options can be set using the config method on the Expression class:

import {Expression} from 'hyoka';
Expression.config({
  precision: 20,
  rounding: 4,
  angles: 'degrees'
});

new Expression('sin(30)').evaluate(); // 0.5

config options can also be passed to the evaluate method. this will override the global config options for that evaluation only:

import {Expression} from 'hyoka';
Expression.config({
  precision: 20,
  rounding: 4,
  angles: 'degrees'
});

// using local config options
new Expression('sin(π/6)').evaluate({angles: 'radians'}); // 0.5
new Expression('1/3').evaluate({decimalPlaces: 3}); // 0.333

// using global config options
new Expression('sin(30)').evaluate(); // 0.5

Supported Operators

<table> <tr> <th>Operator</th> <th>Description</th> <th>type</th> <th>Associativity</th> </tr> <tr> <td>+</td> <td>Addition</td> <td>Binary Infix</td> <td>Left</td> </tr> <tr> <td>-</td> <td>Subtraction</td> <td>Binary Infix</td> <td>Left</td> </tr> <tr> <td>*</td> <td>Multiplication</td> <td>Binary Infix</td> <td>Left</td> </tr> <tr> <td>/</td> <td>Division</td> <td>Binary Infix</td> <td>Left</td> </tr> <tr> <td>%</td> <td>Modulo</td> <td>Binary Infix</td> <td>Left</td> </tr> <tr> <td>^</td> <td>Exponentiation</td> <td>Binary Infix</td> <td>Right</td> </tr> <tr> <td>-</td> <td>Unary minus</td> <td>Unary Prefix</td> <td></td> </tr> <tr> <td>+</td> <td>Unary plus</td> <td>Unary Prefix</td> <td></td> </tr> <tr> <td>!</td> <td>Factorial</td> <td>Unary Postfix</td> <td></td> </tr> </table>

Supported Functions

<table> <tr> <th>Function</th> <th>Description</th> </tr> <tr> <td>acos</td> <td>returns the inverse cosine of an expression</td> </tr> <tr> <td>asin</td> <td>returns the inverse sine of an expression</td> </tr> <tr> <td>atan</td> <td>returns the inverse tangent of an expression</td> </tr> <tr> <td>cos</td> <td>returns the cosine of an expression</td> </tr> <tr> <td>gammln</td> <td>returns the natural log of Γ(x) where x is a valid expression</td> </tr> <tr> <td>max</td> <td>returns the maximum value from a set of expressions</td> </tr> <tr> <td>min</td> <td>returns the minimum value from a set of expressions</td> </tr> <tr> <td>sin</td> <td>returns the sine of an expression</td> </tr> <tr> <td>tan</td> <td>returns the tangent of an expression</td> </tr> <tr> <td>ln</td> <td>returns the natural log of an expression</td> </tr> </table>

Hyoka

Install / Use

README