perf

const { map, find, keyBy } = require('lodash'); function createItems() { const items = []; for (let i = 0; i < 5000; i += 1) { const item = { id: 1, name: `Item ${i}` }; items.push(item); } return items; } function createOnhands() { const items = []; for (let i = 0; i < 5000; i += 1) { const item = { id: 1, cost: 1 }; items.push(item); } return items; } const items = createItems(); const onhands = createOnhands(); function findItemOnhand() { console.time('find'); map(items, (item) => { const itemOnhand = find(onhands, { id: item.id }); return { id: item.id, name: item.name, cost: itemOnhand ? itemOnhand.cost : 0 }; }); console.timeEnd('find'); } function keyByItemOnhand() { console.time('keyBy'); const onhand = keyBy(onhands, 'id'); map(items, (item) => { const itemOnhand = onhand[item.id]; return { id: item.id, name: item.name, cost: itemOnhand ? itemOnhand.cost : 0 }; }); console.timeEnd('keyBy'); } findItemOnhand(); keyByItemOnhand();