Average Sampler

average-sampler.js

/**
 * Generates sample data based on the `options` provided and then calculates the average based on the sample count.
 *
 * @param {Object} options - The options to be used.
 * @param {function(): *} options.generator - The function to be used to generate data per round.
 * @param {number} [options.roundsPerSample=1000] - The number of rounds in which `options.generator` is to be called per sampling.
 * @param {function(value: *): boolean} options.sampler - The function to be used to filter samples from the generated data.
 * @param {number} [options.samples=100] - The number of times samples should be run.
 * @return {number} The calculated average.
 */
function sampleAverage({ generator, roundsPerSample = 1000, sampler, samples = 100 }) {
  function getSample() {
    let i = roundsPerSample;
    const results = [];

    do {
      const result = generator();

      if (sampler(result)) {
        results.push(result);
      }
    } while (--i);

    return results.length;
  }

  const counts = [];

  do {
    counts.push(getSample());
  } while (--samples);

  return counts.reduce((sum, count) => sum + count, 0) / counts.length;
}

An example usage for this is to see how likely it is that a UUID could start with 123:

sampleAverage({
  generator: () => crypto.randomUUID(),
  sampler: (value) => /^123/.test(value)
})
// 0.25