@eluvio/elv-js-helpers/Math/absRelChange.js

A collection of Javascript helper functions used by several Eluvio libraries.

'use strict'
const growth = require('./growth')

const curry = require('../Functional/curry')

// change :: Number -> Number -> Number
// Returns absolute value of change between two numbers, expressed as a proportion of the first value
// e.g. returns 0 if the values are the same, 0.5 if the second value is 50% larger
// Note that 0 is invalid for oldValue, the relative change is Infinity in that case
const absRelChange = curry(
  (oldValue, newValue) => Math.abs(growth(oldValue, newValue))
)

module.exports = absRelChange