cleaner.js

var defaultPrint = (item) => console.log(`Hello, ${item}`)
var myForEach = (list, printFunction = defaultPrint) => {
  list.forEach((item) => printFunction(item))
}

myForEach([1,2,3])
myForEach(["D","K","C"])
myForEach([{name: "Tomba!"},{name: "Neo Cortex"}], (person) => defaultPrint(person.name))
myForEach([{brand: "Ferrari"}, {brand: "Mercedes"}], (car) => defaultPrint(car.brand))
myForEach([{name: "N64", arch: "MIPS"}, {name: "3DS", arch: "ARM9"}], (console) => defaultPrint(`${item.name} - ${item.arch}`))

// in fact we could even use `Array.prototype.forEach` function and avoid the duplication with `myForEach` 
// (which does basically what forEach does)
// var forEach = Array.prototype.forEach
// forEach.call([{name: "Tomba!"},{name: "NeoCortex"}], (person) => defaultPrint(person.name))