Run results for: lodash/keyBy vs native reduce

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:92.0) Gecko/20100101 Firefox/92.0

Browser: Firefox 92

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
lodash/keyBy	6529663.5 Ops/sec
keyBy with native reduce	7473479.5 Ops/sec
keyBy with forEach	6559776.5 Ops/sec
keyBy with for loop	10994048.0 Ops/sec

HTML Preparation code:


<script src='https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.5/lodash.min.js'></script>

Script Preparation code:

var data = [
  { name: 'pi', value: 3.14 },
  { name: 'hundred', value: 100 },
  { name: 'truthy', value: true },
  { name: 'falsy', value: false },
  { name: 'estring', value: '2.71828' },
];

var keyBy = (array, fn) => {
  return array.reduce((acc, value) => {
    acc[fn(value)] = value;
    return acc;
  }, {});
};

var keyByForEach = (array, fn) => {
  var acc = {};
  _.forEach(array, (value) => {
    acc[fn(value)] = value;
  });
  return acc;
};

var keyByForLoop = (array, fn) => {
  var acc = {};
  for (let i = 0; i < array.length; i++) {
    acc[fn(array[i])] = array[i];
  }
  return acc;
};

Tests:

lodash/keyBy
_.keyBy(data, (v) => v.name);
keyBy with native reduce
keyBy(data, (v) => v.name);
keyBy with forEach
keyByForEach(data, (v) => v.name);
keyBy with for loop
keyByForLoop(data, (v) => v.name);

Run results for: lodash/keyBy vs native reduce

lodash/keyBy

keyBy with native reduce

keyBy with forEach

keyBy with for loop