Run results for: lodash flattenDeep vs js native

Run details:

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/115.0

Browser: Firefox 115

Operating system: Ubuntu

Device Platform: Desktop

Date tested: one year ago

Test name	Executions per second
_.flattenDeep	9649040.0 Ops/sec
// Native	2041021.0 Ops/sec
Native(ES2019)	12327130.0 Ops/sec
native 2	3437265.0 Ops/sec

HTML Preparation code:

<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

Script Preparation code:

var elements = [1, [2, [3, [4]], 5]];

const flattenDeep = (arr) => Array.isArray(arr)
  ? arr.reduce( (a, b) => a.concat(flattenDeep(b)) , [])
  : [arr];

const flattenDeepL = (arr) => arr.flatMap((subArray, index) => Array.isArray(subArray) ? flattenDeepL(subArray) : subArray);

Tests:

_.flattenDeep
_.flattenDeep(elements);
// Native
const flattenDeep = (arr) => Array.isArray(arr) ? arr.reduce( (a, b) => a.concat(flattenDeep(b)) , []) : [arr]; flattenDeep(elements)
Native(ES2019)
elements.flat(Infinity)
native 2
const flattenDeep = (arr) => arr.flatMap((subArray, index) => Array.isArray(subArray) ? flattenDeep(subArray) : subArray) flattenDeep(elements)

Run results for: lodash flattenDeep vs js native

_.flattenDeep

// Native

Native(ES2019)

native 2