Helper functions I didn't realize I wanted until I wrote them a few times in several different projects. Uses ES6 module syntax.

functional_helpers.js

// ====================
// =  OBJECT HELPERS  =
// ====================
export const set = (obj, prop, val) => {
  obj[prop] = val
  return obj
}

export const extractObj = (obj, prop) =>
  Object.keys(obj).map(key =>
    obj[key][prop])

export const simplify = (obj, prop) =>
  Object.keys(obj)
    .reduce((acc, key) =>
      set(acc, key, obj[key][prop]), {})


// ===================
// =  ARRAY HELPERS  =
// ===================

export const extractArr = (arr, prop) =>
  arr.map(val => val[prop])

export const span = (length, start = 0) =>
  [...Array(length).keys()]
    .map(num =>
      num + start)

export const range = function(start, end = start) {
  if (arguments[1] === undefined) a = 0
  return span(end - start, start)
})


// ======================
// =  OMNIVORE HELPERS  =
// ======================
export const extract = (thing, prop) => {
  if (Array.isArray(thing))
    return extractArr(thing, prop)
  return extractObj(thing, prop)
}