Run results for: Array.map().filter(Boolean) vs Array.flatMap() vs Array.reduce()

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:133.0) Gecko/20100101 Firefox/133.0

Browser: Firefox 133

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Benchmark engine: Benchmark.js

Array.flatMap()

173K/s

Array.map().filter(Boolean)

160K/s

Array.reduce()

26K/s

View exact numbers

Test name	Executions per second
✓ Array.flatMap()	173,451 Ops/sec
Array.map().filter(Boolean)	159,742 Ops/sec
Array.reduce()	26,364 Ops/sec

Script Preparation code:

var a1 = ['', '1231237', '', '', '', '', 'ergre', '', '', '', '', 'asdf1134', '', '', '123'];
var a2 = ['1231237', '123', '1231237', '123', '1231237', '', '123sdfsdf', 'sdfsdf'],
    result,
    a1 = a1.flatMap((s, i) => i % 2 ? a1 : a2),
    a2 = a2.flatMap((s, i) => i % 2 ? a2 : a1);

Tests:

Array.map().filter(Boolean)
result = a1.map(s => a2.includes(s) && s).filter(Boolean);
Array.flatMap()
result = a1.flatMap(s => s && a2.includes(s) ? [s] : []);
Array.reduce()
result = a1.reduce((acc, s) => (s && a2.includes(s) ? [...acc, s] : acc), []);

Run results for: Array.map().filter(Boolean) vs Array.flatMap() vs Array.reduce()

comparison of filtering out falsy values from an array

Array.map().filter(Boolean)

Array.flatMap()

Array.reduce()