1.2.0 • Public • Published



Simplify time measurements.

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Table of Contents


Platform Status

To use library you need to have node and npm installed in your machine:

  • node >=10
  • npm >=6

Package is continuously tested on darwin, linux and win32 platforms. All active and maintenance LTS node releases are supported.


To install the library run the following command

  npm i --save vesta


Minimal Configuration

import BenchMark from 'vesta';

const bench = new BenchMark();

await Promise.all([ 10, 20, 30, 40, 50, 60 ].map(async i => {
    const bi = bench.start('pause');

    await pause(i);

// ------------------------
// Label: pause
// Total: 6
// Mean: 35.166666666666664
// Q25: 22.75
// Q75: 47.5


in case of consecutive measurements use next api:

import BenchMark, { JSONReporter } from 'vesta';

const bench = new BenchMark();

bench.sequence('before cycle');

for (const iter of [ 1, 2, 3 ]) {
    const iteration = bench.iteration(iter);

    iteration.sequence('before iteration');
    await pause(15);
    iteration.sequence('15ms gone');
    await pause(10);
    iteration.sequence('after 10ms more');
    await pause(20);
    iteration.sequence('end of the iteration');

bench.sequence('after cycle');

console.log( JSONReporter()));
// [{"label":"before cycle","benchmark":0},{"label":"after cycle","benchmark":139},{"label":"before iteration","total":3,"mean":0,"q25":0,"q75":0},{"label":"15ms gone","total":3,"mean":15.333333333333334,"q25":15,"q75":15.5},{"label":"after 10ms more","total":3,"mean":10,"q25":10,"q75":10},{"label":"end of the iteration","total":3,"mean":20,"q25":20,"q75":20}]


Timers are used to fix the moment of time. By default Timer is autodetected among process.hrtime.bigint() or new Date() depending on your environment.

All timers available from package:

import { Timer, ProcessHrtime, PerformanceNow } from 'vesta';

you can pass any of them explicitly:

import { Timer } from 'vesta';

class customTimer extends Timer {}

const bench = new BenchMark({
    counter : new customTimer()

to implement own timer it is recomended to extends Timer and follow it's interfece.


There are two reports available:

  • JSONReporter - report in json format, usefull for external export.
  • PlainReporter - used by default.

use custom reporter on report generation:

import BenchMark, { JSONReporter } from 'vesta';

const bench = new BenchMark();

const report = JSON.parse( JSONReporter()));

to pretty print numbers in report use:

import BenchMark, { PlainReporter } from 'vesta';

const bench = new BenchMark(); PlainReporter(), { pretty: true });

or pass pretty as configuration object:

import BenchMark, { JSONReporter } from 'vesta';

const bench = new BenchMark({});

await pause(2500);

console.log( JSONReporter(), {
        pretty : {
            exclude : [ 'total' ],
            include : [ 'mean', 'benchmark' ]

// [
//     { label: 'before', benchmark: 0 },
//     { label: 'after', benchmark: '2s 504ms' }
// ];


  • include - array with metric names, for which prettifier will be added.
  • exclude - array with metric names, for which prettifier won't be added.


pass next options to BenchMark properties:

  • shortSingleObservations (boolean): use short report when there are only 1 observation. true by default.
  • counter (Timer): time measurer. autodetector by default.

Custom mertics

To enrich your reports, you can easily introduce new metrics to the benchmark calculations in your JavaScript code. Utilize the calculate() method along with metrics and items objects within the BenchMark instance:

import BenchMark from 'vesta';

const bench = new BenchMark({});

    metrics : {
        over25ms : arr => arr.filter(i => i > 25).length, // number of benchmarks longer then 25ms,

        // Omit calculation for quantiles
        q25 : null,
        q75 : null
    items : {
        // Identify benchmarks over the mean value
        overMean : (arr, metrics) => arr.filter(i => i.bench > metrics.mean).map(i => i.payload)

Some of the other custom metrics you might be looking for:

  • include a metric for the mean value over the last 10 records exclusively:
metrics : {
    last10 : arr => BenchMark.metrics.mean(arr.slice(-10));

These additions allow you to tailor the benchmarks and generate more comprehensive reports tailored to your specific needs.


Use the same API to benchmark memory usage:

import { Memory, PlainReporter } from 'vesta';

const bench = new Memory();

const b1 = bench.start('before');
const a = Array.from({ length: 1e7 });


console.log( PlainReporter(), { pretty: true }));

//   ------------------------
// Label: before
// Rss: 76.05MB
// HeapTotal: 76.3MB
// HeapUsed: 76.29MB
// External: 0MB
// ArrayBuffers: 0MB


Make the changes to the code and tests. Then commit to your branch. Be sure to follow the commit message conventions. Read Contributing Guidelines for details.

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