es6 Range

range.js

const range = (start, end, step = 1) => {
  const forLoop = fn => {
    for (let x = start; x <= end; x += step) fn(x)
  }

  const between = (v, start, end) => v >= start && v <= end
  const hasValue = v => between(v, start, end) || between(v, end, start)

  const iterate = function* (mapFn) {
    for (let x = start; x <= end; x += step) yield mapFn ? mapFn(x) : x
  }

  const rangeObj = {}

  const createProp = v => ({ value: v })
  const map = createProp(mapFn => [...iterate(mapFn)])
  const forEach = createProp(forLoop)
  const includes = createProp(v => {
    for (let x = start; x <= end; x += step) {
      if (v === x) return true
    }
    return false
  })
  const has = createProp(hasValue)

  Object.defineProperties(rangeObj, {
    map,
    forEach,
    includes,
    has,
  })
  return rangeObj
}