Map vs obj read benchmark

map_vs_obj_benchmark.js

async function checkAvgPerf() {
  const numberOfReads = 100000;
  const numberOfTests = 100;
  const eps = 0.000001;
  const mapAvg = [];
  const objAvg = [];

  let mapSlowerOnAvgTimes = 0;
  let objSlowerOnAvgTimes = 0;
  let equalTimes = 0;

  function sum(arr) {
    return arr.reduce((acc, v) => acc + v, 0);
  }

  async function checkReadPerf() {
    return new Promise((resolve, reject) => {
      setTimeout(
        () => {
          try {
            const key = 'a';
            const value = 100;

            const map = new Map();
            map.set('a', 100);

            const obj = {};
            obj['a'] = 100;

            const readValueFromMap = () => map.get('a');
            const readValueFromObj = () => obj['a'];

            let mapTimes = 0;
            let objTimes = 0;

            for (let i = 0; i < numberOfReads; i++) {
              const startTime = performance.now();

              readValueFromMap();
              const mapTime = performance.now();

              readValueFromObj();
              const objTime = performance.now();

              mapTimes += mapTime - startTime;
              objTimes += objTime - mapTime;
            }

            const mapTimesAvg = mapTimes / numberOfReads;
            const objTimesAvg = objTimes / numberOfReads;

            resolve({
              mapTimesAvg,
              objTimesAvg,
              slowerOnAvg:
                mapTimesAvg - objTimesAvg > eps
                  ? 'map'
                  : objTimesAvg - mapTimesAvg > eps
                  ? 'obj'
                  : 'equal',
            });
          } catch (e) {
            reject(e);
          }
        },
        Math.floor(Math.random() * 5),
      );
    });
  }

  for (let i = 0; i < numberOfTests; i++) {
    const results = await checkReadPerf();
    mapAvg.push(results.mapTimesAvg);
    objAvg.push(results.objTimesAvg);

    if (results.slowerOnAvg === 'map') {
      mapSlowerOnAvgTimes++;
    } else if (results.slowerOnAvg === 'obj') {
      objSlowerOnAvgTimes++;
    } else if (results.slowerOnAvg === 'equal') {
      equalTimes++;
    } else {
      throw new Error(`Unexpected result "${results.slowerOnAvg}"`);
    }
  }

  if (mapSlowerOnAvgTimes > objSlowerOnAvgTimes) {
    console.log(
      `Map is slower in most tests after ${numberOfTests} tests and ${numberOfReads} reads each (${mapSlowerOnAvgTimes} vs ${objSlowerOnAvgTimes} tests, eps=${eps})`,
    );
  } else if (mapSlowerOnAvgTimes < objSlowerOnAvgTimes) {
    console.log(
      `Obj is slower in most tests after ${numberOfTests} tests and ${numberOfReads} reads each (${mapSlowerOnAvgTimes} vs ${objSlowerOnAvgTimes} tests, eps=${eps})`,
    );
  } else {
    console.log(
      `Map and obj have equal read times in most tests after ${numberOfTests} tests and ${numberOfReads} reads each (${mapSlowerOnAvgTimes} vs ${objSlowerOnAvgTimes} tests, eps=${eps})`,
    );
  }

  console.log(
    `Map average read time is ${sum(mapAvg) / numberOfTests}`,
  );
  console.log(
    `Obj average read time is ${sum(objAvg) / numberOfTests}`,
  );
}