Run results for: Object for...in vs for...index 2【no hasOwn】

Run details:

User agent: Mozilla/5.0 (Android 15; Mobile; rv:148.0) Gecko/148.0 Firefox/148.0

Browser: Firefox Mobile 148

Operating system: Android

Device Platform: Mobile

Date tested: 6 months ago

Benchmark engine: Benchmark.js

forIn

3.9M/s

forIndex

3.8M/s

View exact numbers

Test name	Executions per second
✓ forIn	3,905,115 Ops/sec
forIndex	3,758,336 Ops/sec

HTML Preparation code:

<!--your preparation HTML code goes here-->

Script Preparation code:

// 生成测试对象
const createTestObject = (size) => {
  const obj = {};
  for (let i = 0; i < size; i++) {
    obj[`key${i}`] = i;
  }
  return obj;
};

// 测试 for...in
function testForIn(obj) {
  const start = performance.now();
  for (const key in obj) {
      const value = obj[key];
  }
  return performance.now() - start;
}

// 测试 Object.keys + for
function testObjectKeysFor(obj) {
  const start = performance.now();
  const keys = Object.keys(obj);
  for (let i = 0; i < keys.length; i++) {
    const key = keys[i];
    const value = obj[key];
  }
  return performance.now() - start;
}

// 运行测试
const obj = createTestObject(10);

Tests:

forIn
testForIn(obj)
forIndex
testObjectKeysFor(obj)