Run results for: lodash groupBy vs Object.groupBy 500k

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser: Chrome 130

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 18 days ago

Test name	Executions per second
Lodash with _.mapValues and _.omit	2.8 Ops/sec
Native reduce Grouping with Destructuring	14.5 Ops/sec
Custom reduce with Object.keys Filtering	8.4 Ops/sec
Lodash Grouping with Native Key Removal	44.2 Ops/sec

HTML Preparation code:

<script src="https://cdn.jsdelivr.net/npm/lodash@4.17.21/lodash.min.js"></script>

Script Preparation code:

const max2 = 500000;
var rows = [];

for (let i = 0; i <= max2; i++) {  // Use `let` for `i` as it’s updated in each loop iteration
  rows.push({
    id: i,
    task_id: i % 1000,
    name: `Task ${i}`,
    status: i % 2 === 0 ? 'active' : 'inactive',
    description: `Description for task ${i}`,
    priority: Math.floor(Math.random() * 5) + 1
  });
}

Tests:

Lodash with _.mapValues and _.omit
const lodashMapValuesOmitGrouped = _.mapValues(_.groupBy(rows, 'task_id'), group => group.map(row => _.omit(row, 'task_id')) );
Native reduce Grouping with Destructuring
const nativeReduceGrouped = rows.reduce((acc, row) => { const { task_id, ...rest } = row; // Exclude `task_id` using destructuring if (!acc[task_id]) acc[task_id] = []; // Initialize array for this `task_id` acc[task_id].push(rest); // Add the item without `task_id` to the group return acc; }, {});
Custom reduce with Object.keys Filtering
const customReduceGrouped = rows.reduce((acc, row) => { if (!acc[row.id]) acc[row.id] = []; // Initialize an array for each unique id const rowData = Object.keys(row).reduce((obj, key) => { if (key !== 'id') obj[key] = row[key]; // Exclude 'id' to avoid nesting return obj; }, {}); acc[row.id].push(rowData); return acc; }, {});
Lodash Grouping with Native Key Removal
const lodashGroupedWithDelete = _.groupBy(rows, 'task_id'); Object.values(lodashGroupedWithDelete).forEach(group => { group.forEach(item => { delete item.task_id; // Remove `task_id` directly from each item }); });

Run results for: lodash groupBy vs Object.groupBy 500k

Lodash with _.mapValues and _.omit

Native reduce Grouping with Destructuring

Custom reduce with Object.keys Filtering

Lodash Grouping with Native Key Removal