@beyondessential/arithmetic

Utility to evaluate BODMAS arithmetic formulas. It is an implementation of the shunting yard algorithm.

Installation

With yarn:

yarn add @beyondessential/arithmetic

With npm:

npm add @beyondessential/arithmetic

API

formulaText must be in BODMAS format.

runArithmetic(formulaText: string, values?: Record<string, string | number>): number

Usage example:

import { runArithmetic } from '@beyondessential/arithmetic';

const value = runArithmetic('(-1 + 2.5) / 3');
console.log(value); // 0.5

const valueWithVariable = runArithmetic('2 * four', {
  four: 4,
});
console.log(valueWithVariable); // 8

getVariables(formulaText: string): string[]

Usage example:

import { getVariables } from '@beyondessential/arithmetic';

const variables = getVariables('(-a * b - 1) / (c + 3)');
console.log(variables); // ['a', 'b', 'c']

formulaText operators

Note: All operators are case insensitive. Operator | Example | Description -|-|- + | 1 + 1 | Addition - | 1 - 1 | Subtraction * or x | 1 * 1 or 1 x 1 | Multiplication / | 1 / 1 | Division ()| 1 / (1 + 1) | Brackets - | -1 | Unary minus max | max(1, 2, 3) | Takes the maximum value of it's arguments. -Infinity if given none