FindLcm.js

/*
 author: PatOnTheBack
 license: GPL-3.0 or later

 Modified from:
 https://github.com/TheAlgorithms/Python/blob/master/maths/findLcm.py

 More about LCM:
 https://en.wikipedia.org/wiki/Least_common_multiple
*/

'use strict'

import { findHCF } from './FindHcf'

// Find the LCM of two numbers.
const findLcm = (num1, num2) => {
 // If the input numbers are less than 1 return an error message.
 if (num1 < 1 || num2 < 1) {
 throw Error('Numbers must be positive.')
 }

 // If the input numbers are not integers return an error message.
 if (num1 !== Math.round(num1) || num2 !== Math.round(num2)) {
 throw Error('Numbers must be whole.')
 }

 // Get the larger number between the two
 const maxNum = Math.max(num1, num2)
 let lcm = maxNum

 while (true) {
 if (lcm % num1 === 0 && lcm % num2 === 0) return lcm
 lcm += maxNum
 }
}

// Typically, but not always, more efficient
const findLcmWithHcf = (num1, num2) => {
 // If the input numbers are less than 1 return an error message.
 if (num1 < 1 || num2 < 1) {
 throw Error('Numbers must be positive.')
 }

 // If the input numbers are not integers return an error message.
 if (num1 !== Math.round(num1) || num2 !== Math.round(num2)) {
 throw Error('Numbers must be whole.')
 }

 return (num1 * num2) / findHCF(num1, num2)
}

export { findLcm, findLcmWithHcf }