Run results for: Finding duplicates

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; SM-G9650) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Mobile Safari/537.36

Browser: Chrome Mobile 87

Operating system: Android

Device Platform: Mobile

Date tested: 3 years ago

Test name	Executions per second
Filter	19.0 Ops/sec
Group by	1115.9 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 max = 5000;

var arr = [];
for (let i = 0; i < max; i++) {
  arr.push({ value: i});
  // create an occasional duplicate
  if (i % 10 === 0) {
    arr.push({ value: i});
  }
}

Tests:

Filter
var duplicates = arr.filter((item, _, items) => items.find(dupItem => dupItem.value === item.value));
Group by
var grouped = _.groupBy(arr, item => item.value); var duplicates1 = _.flatten(_.filter(grouped, group => group.length > 1));

Run results for: Finding duplicates

Filter

Group by