Run results for: Map or Reduce or Lodash GroupBy

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.71 Safari/537.36

Browser: Chrome 97

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
gp	447141.1 Ops/sec
map	821609.8 Ops/sec
reduce	888383.8 Ops/sec

Script Preparation code:

var MAX_SAFE_INTEGER = 9007199254740991

function arrayReduce(array, iteratee, accumulator, initAccum) {
  let index = -1
  const length = array == null ? 0 : array.length

  if (initAccum && length) {
    accumulator = array[++index]
  }
  while (++index < length) {
    accumulator = iteratee(accumulator, array[index], index, array)
  }
  return accumulator
}


function baseFor(object, iteratee, keysFunc) {
  const iterable = Object(object)
  const props = keysFunc(object)
  let { length } = props
  let index = -1

  while (length--) {
    const key = props[++index]
    if (iteratee(iterable[key], key, iterable) === false) {
      break
    }
  }
  return object
}

function isLength(value) {
  return typeof value === 'number' &&
    value > -1 && value % 1 == 0 && value <= MAX_SAFE_INTEGER
}

function isArrayLike(value) {
  return value != null && typeof value !== 'function' && isLength(value.length)
}


function baseForOwn(object, iteratee) {
  return object && baseFor(object, iteratee, keys)
}


function baseEach(collection, iteratee) {
  if (collection == null) {
    return collection
  }
  if (!isArrayLike(collection)) {
    return baseForOwn(collection, iteratee)
  }
  const length = collection.length
  const iterable = Object(collection)
  let index = -1

  while (++index < length) {
    if (iteratee(iterable[index], index, iterable) === false) {
      break
    }
  }
  return collection
}


function baseReduce(collection, iteratee, accumulator, initAccum, eachFunc) {
  eachFunc(collection, (value, index, collection) => {
    accumulator = initAccum
      ? (initAccum = false, value)
      : iteratee(accumulator, value, index, collection)
  })
  return accumulator
}


function reduce(collection, iteratee, accumulator) {
  const func = Array.isArray(collection) ? arrayReduce : baseReduce
  const initAccum = arguments.length < 3
  return func(collection, iteratee, accumulator, initAccum, baseEach)
}


var hasOwnProperty = Object.prototype.hasOwnProperty

function baseAssignValue(object, key, value) {
  if (key == '__proto__') {
    Object.defineProperty(object, key, {
      'configurable': true,
      'enumerable': true,
      'value': value,
      'writable': true
    })
  } else {
    object[key] = value
  }
}

function groupBy(collection, iteratee) {
  return reduce(collection, (result, value, key) => {
    key = iteratee(value)
    if (hasOwnProperty.call(result, key)) {
      result[key].push(value)
    } else {
      baseAssignValue(result, key, [value])
    }
    return result
  }, {})
}

var arr = [6.1, 4.2, 6.3];

Tests:

gp
const lm = groupBy(arr, Math.floor)
map
const m = new Map(); for (const v of arr) { const k = Math.floor(v); const temp = m.get(k) ?? []; temp.push(v); m.set(k, temp) }
reduce
const rm = arr.reduce((acc, v) => { const k = Math.floor(v) + ''; (acc[k] || (acc[k] = [])).push(v) return acc; }, {})

Run results for: Map or Reduce or Lodash GroupBy

Map or Reduce or Lodash GroupBy

gp

map

reduce