Run results for: Object for...in vs for...index 2

Run details:

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Mobile Safari/537.36 EdgA/136.0.0.0

Browser: Chrome Mobile 136

Operating system: Android

Device Platform: Mobile

Date tested: 9 months ago

forIndex

9K/s

forIn

7K/s

View exact numbers

Test name	Executions per second
✓ forIndex	8,807 Ops/sec
forIn	6,657 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) {
    if (Object.hasOwn(obj, key)) {
      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(1e3);

Tests:

forIn
testForIn(obj)
forIndex
testObjectKeysFor(obj)