Browser or Node.js JavaScript performance test (jsperf): for..in vs for + Object.keys vs for..of + Object.keys vs for..of + Object.entries

perf.js

// Run each test in the new tab
const { performance, PerformanceObserver } = typeof window !== 'undefined' ? window : require('perf_hooks');

function test() {
  let objectSize = 30;
  let iterations = 7000;

  const values = {
    'ENTRIES': 0,
    'FOR-OF-KEYS': 0,
    'FOR-KEYS': 0,
    'FOR-IN': 0,
    'FOR-IN-OWN': 0,
  };

  const observer = new PerformanceObserver((items) => {
    for (const entry of items.getEntries()) {
      values[entry.name] += entry.duration;
    }
    
    console.log(Object.entries(values).sort((a, b) => a[1] - b[1]));
    
    performance.clearMarks();
    observer.disconnect();   
  });

  observer.observe({ entryTypes: ['measure'], buffered: true });

  function generateObject() {
    let obj = {};
    for (let i = 0; i < objectSize; i++) {
      obj['key-blabla' + i] = 'val' + i;
    }
    return obj;
  }

  console.log(
    'Starting performance test with %d object size and %d iterations',
    objectSize,
    iterations,
  );

  for (let i = 0; i < iterations; i++) {
    let obj = generateObject();

    // Object.entries
    performance.mark('A');
    for(const [key, value] of Object.entries(obj)) {
      key + value
    };
    performance.mark('B');
    performance.measure('ENTRIES', 'A', 'B');

    // Object.Keys
    performance.mark('A');
    for (const key of Object.keys(obj)) {
      key + obj[key];
    }
    performance.mark('B');
    performance.measure('FOR-OF-KEYS', 'A', 'B');

    // For
    performance.mark('A');
    for (let i = 0, keys = Object.keys(obj), len = keys.length; i < len; i++) {
      keys[i] + obj[keys[i]];
    }
    performance.mark('B');
    performance.measure('FOR-KEYS', 'A', 'B');

    // For In
    performance.mark('A');
    for (const key in obj) {
      key + obj[key];
    }
    performance.mark('B');
    performance.measure('FOR-IN', 'A', 'B');

    // For In + Own
    performance.mark('A');
    for (const key in obj) {
      if (obj.hasOwnProperty(key)) {
        key + obj[key];
      }
    }
    performance.mark('B');
    performance.measure('FOR-IN-OWN', 'A', 'B');
  }
}

test();