Benchmark: reduce.concat() vs flatMap()

Script Preparation code:

var flag = {
	a: {'truthy': true, 'falsey': false, 'only-in-a': true},
	b: {'truthy': true, 'falsey': false, 'only-in-b': true},
	unused: {'truthy': true, 'falsey': false},
};
var rollNames = ['a', 'b', 'missing'];

Tests:

reduce + Array.prototype.concat
var other = rollNames.flatMap(rollName => // convert flag object to array containing the names of all fields with a truthy value Object.entries(flag[rollName] ?? {}).reduce((opts, [key, value]) => opts.concat(value ? key : []), []) ).reduce((unique, option) => { // ensure option entries are unique return unique.includes(option) ? unique : unique.concat(option); }, []);
Array.prototype.flatMap
var other = [...new Set(rollNames.flatMap(rollName => // convert flag object to array containing the names of all fields with a truthy value Object.entries(flag[rollName] ?? {}).flatMap(([key, value]) => value ? [key] : []) ))];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce + Array.prototype.concat
Array.prototype.flatMap

Fastest: N/A

Slowest: N/A

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Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:123.0) Gecko/20100101 Firefox/123.0

Browser/OS: Firefox 123 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
reduce + Array.prototype.concat	817138.8 Ops/sec
Array.prototype.flatMap	798135.8 Ops/sec

reduce.concat() vs flatMap() (version: 0)

Compare the new ES6 spread operator with the traditional concat() method

Comparing performance of: reduce + Array.prototype.concat vs Array.prototype.flatMap

Created: 3 years ago by: Guest

Jump to the latest result

reduce + Array.prototype.concat

Array.prototype.flatMap

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A