Benchmark: getOwnPropertyNames() vs Object.keys() vs for ... in

Script Preparation code:

var obj = {
  $props : ['a','b','c'],
  a:1,
  b:2,
  c:3
}

Tests:

Object.keys()
const arr = Object.keys(obj); let n = 0; for (let i = 0; i < arr.length; i++) { const k = arr[i]; if (k.charAt(0) == '$') continue; n++; }
getOwnPropertyNames()
const arr = Object.getOwnPropertyNames(obj); let n = 0; for (let i = 0; i < arr.length; i++) { const k = arr[i]; if (k.charAt(0) == '$') continue; n++; }
for ... in loop
let n = 0; for (const k in obj) { if (k.charAt(0) == '$') continue; n++; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.keys()
getOwnPropertyNames()
for ... in loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36

Browser/OS: Chrome 119 on Mac OS X 10.15.7

View result in a separate tab

for ... in loop

26.7M/s

Object.keys()

9.9M/s

getOwnPropertyNames()

9.4M/s

View exact numbers

Test name	Executions per second
✓ for ... in loop	26,696,090 Ops/sec
Object.keys()	9,906,305 Ops/sec
getOwnPropertyNames()	9,410,627 Ops/sec

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark test case.

**Benchmark Name**: `getOwnPropertyNames() vs Object.keys() vs for ... in`

This test compares three different ways to iterate over an object's properties:

1. Using `Object.getOwnPropertyNames()`
2. Using `Object.keys()`
3. Using a `for ... in` loop

**Test Case Descriptions**

Each test case is a separate JavaScript code snippet that performs the iteration and counting of property names.

1. **Object.keys()**: This test uses `Object.keys()` to get an array of own property names, then iterates over this array using a `for` loop.
2. **getOwnPropertyNames()**: This test uses `Object.getOwnPropertyNames()` to get an array of all property names (own and inherited), then iterates over this array using a `for` loop.
3. **for ... in**: This test uses a traditional `for ... in` loop to iterate directly over the object's properties.

**Library/Feature Used**

None, these are built-in JavaScript features.

**Pros and Cons of each approach**

1. **Object.keys()**:
	* Pros: Returns only own property names, simpler syntax.
	* Cons: May be slower for large objects due to overhead of `Object.keys()` method.
2. **getOwnPropertyNames()**:
	* Pros: Also returns inherited property names, which can be useful in some cases.
	* Cons: May return more properties than needed, potentially slower for large objects.
3. **for ... in**:
	* Pros: Simplest syntax, no overhead of method calls.
	* Cons: Iterates over all own and inherited property names, including prototype chain.

**Other Alternatives**

There are other ways to iterate over an object's properties, such as:

1. Using a `forEach()` loop or a `for (const key in obj) { ... }` loop without the `hasOwnProperty()` check.
2. Using a library like Lodash or Underscore.js, which provide their own iteration functions.

However, these alternatives are not compared in this benchmark test case.

**Benchmark Results**

The latest benchmark results show:

1. **for ... in**: ~26.7 million executions per second
2. **Object.keys()**: ~9.4 million executions per second
3. **getOwnPropertyNames()**: ~9.4 million executions per second

These results indicate that the `for ... in` loop is the fastest approach, likely due to its simplicity and lack of method overhead. However, it's essential to consider the trade-offs and potential use cases for each approach when choosing an iteration method.

getOwnPropertyNames() vs Object.keys() vs for ... in (version: 0)

Comparing performance of: `Object.keys() vs getOwnPropertyNames() vs for ... in loop`

Created: 2 years ago by: Guest

Go to the latest result

Object.keys()

getOwnPropertyNames()

for ... in loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

getOwnPropertyNames() vs Object.keys() vs for ... in (version: 0)

Comparing performance of: Object.keys() vs getOwnPropertyNames() vs for ... in loop

Created: 2 years ago by: Guest

Go to the latest result

Object.keys()

getOwnPropertyNames()

for ... in loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

Related benchmarks

Comparing performance of: `Object.keys() vs getOwnPropertyNames() vs for ... in loop`