@jsperf.dev/benchmark

Getting Started

This package exports an initialized instance of the Benchmark class from @jsperf.dev/core. It is initialized with all configuration properties set to their documented defaults.

Import with const benchmark = require('@jsperf.dev/benchmark').default for CJS, or import benchmark from '@jsperf.dev/benchmark' for ESM

Start the benchmarking scipt using one of the import methods:

const benchmark = require("@jsperf.dev/benchmark").default;

Some configuration values can be modified. Make sure this happens within the same execution step of the main script. The configurable properties can be found in the @jsperf.dev/core docs under Benchmark - Instance Properties.

For example, the sumOfSquares example sets its meta property:

const N = 10000;

benchmark.meta = {
  title: "Sum of Squares",
  description: `Compare 3 seperate algorithms for calculating the sum of the square of all numbers from 0 to ${N}`,
};

Then, begin by defining necessary lifecycle methods. The four available are beforeAll, beforeEach, afterAll, and afterEach.

A benchmark suite has a context that is passed to every lifecycle method and run scripts. The recommended way to set the context is during the beforeAll lifecycle method.

For example, the context should contain normalized input values or methods that all of the run scripts should use.

From the sumOfSquares example:

benchmark.beforeAll((context) => {
  Object.assign(context, {
    list: Array.from({ length: 100 }, (_, i) => i),
    square: (n) => n ** 2,
  });
});

Similarly, the after lifecycle methods can be used to assert that the results of each run script are correct. Continuing with the sumOfSquares example, the following block asserts that the list in the context remains the same length, and that the result from each run is the expected value.

benchmark.afterEach(({ list }, sum) => {
  assert(list.length === 100, `list has 100 items`);
  assert(sum === 328350, `sum is ${sum}`);
});

Each run should be designed to make use of the values in context, and then be sure to return the computed result so it can be verified in the after blocks.

// examples/sumOfSquares/reduce.js
module.exports.default = ({ list, square }) => {
  return list.reduce((acc, i) => (acc += square(i)), 0);
};

Finally, back in the benchmarking script, add runs using the run method. The first argument must be a unique identifier, and the second argument must be the absoulte path to the run script. The sumOfSquares example is written in CommonJS so it makes use of path.resolve() and __dirname, but ESM users can make use of a path resolver like: path.resolve(path.dirname(url.fileURLToPath(import.meta.url)), 'reduce.js').

benchmark.run("reduce", path.resolve(__dirname, "reduce.js"));

The benchmark script can be executed using node and information about the execution will be logged to stdout. Below is a simplified output of the sumOfSquares example.

{ "script": "Sum of Squares" }
{ "description": "Compare 3 seperate algorithms for calculating the sum of the square of all numbers from 0 to 100" }
{ "samples": 10}
{ "results": [
    { "run": "quick sum", "medianTime": 0.010526984930038452 },
    { "run": "forEach", "medianTime": 0.010573983192443848 },
    { "run": "reduce", "medianTime": 0.01349899172782898 }
]}

API

Default: benchmark

• type: Benchmark

Function: setLogger(logger)

Arguments:

• logger - pino.Logger

Use this method to override the default pino logger instance.

Testing

Execute tests using pnpm test