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

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/89.0.4389.90 Safari/537.36

Browser: Chrome 89

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 3 years ago

Test name	Executions per second
Array.map().filter(Boolean)	49677.3 Ops/sec
Array.flatMap()	51303.1 Ops/sec

Script Preparation code:

var arr1 = ['', '1231237', '', '', '', '', 'ergre', '', '', '', '', 'asdf1134', '', '', '123'];
var arr2 = ['1231237', '123','1231237', '123','1231237', '', '123sdfsdf','sdfsdf'];

Tests:

Array.map().filter(Boolean)
var result = arr1.map(str => str && arr2.includes(str) && str).filter(Boolean); console.log(result);
Array.flatMap()
var result = arr1.flatMap(str => str && arr2.includes(str) && str ? [str] : []); console.log(result);

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

comparison of filtering out falsy values from an array

Array.map().filter(Boolean)

Array.flatMap()