functional-javascript-workshop/exercises/implement_map_with_reduce/solution/solution.js

The basics of functional programming in JavaScript. No libraries required.

module.exports = function arrayMap(arr, fn, thisArg) {
  return arr.reduce(function(acc, item, index, arr) {
    acc.push(fn.call(thisArg, item, index, arr))
    return acc
  }, [])
}