Merge

mergeWith.js

import mergeWith from 'lodash/mergeWith'

const m1 = { a: 1, b: 2 }
const m2 = { a: 9, c: 3 }
const m3 = { a: 4, b: 5, d: 7 }

// Lodash version
// merge objects with customizer
mergeWith(m1, m2, m3, (objValue, srcValue, key, object) => {
    if (Object.prototype.hasOwnProperty.call(object, key)) {
        return Array.isArray(objValue) ? [...objValue, srcValue] : [objValue, srcValue]
    } else {
        return srcValue
    }
}) // ?


// Two pointer version