Benchmark: for-in vs for-of Object.keys 2

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in
for (let i=10000; i > 0; i--) { for (let key in obj) { let x = key in obj; } }
for-of Object.keys
for (let i=10000; i > 0; i--) { let keys = Object.keys(obj); for (let key of keys) { let x = key in obj; } }
for-of Object.keys includes
for (let i=10000; i > 0; i--) { let keys = Object.keys(obj); for (let key of keys) { let x = keys.includes(key); } }
for-of Object.keys hasOwnProperty
for (let i=10000; i > 0; i--) { let keys = Object.keys(obj); for (let key of keys) { let x = Object.hasOwnProperty(obj, key); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
for-of Object.keys
for-of Object.keys includes
for-of Object.keys hasOwnProperty

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its options.

**Benchmark Overview**

The benchmark measures the performance of three different approaches to iterate over an object's keys:

1. `for-in` loop
2. Using `Object.keys()` method with `for...of` loop
3. Using `includes()` method with `for...of` loop
4. Using `hasOwnProperty()` method with `for...of` loop

**Options Compared**

The benchmark compares the performance of these four approaches:

* `for-in` loop: This is an older way of iterating over object properties using a loop.
* `Object.keys()` method with `for...of` loop: This approach uses the `Object.keys()` method to get an array of keys, and then iterates over it using a `for...of` loop.
* `includes()` method with `for...of` loop: This approach uses the `includes()` method to check if a key is present in the object, and then iterates over the object's keys using a `for...of` loop.
* `hasOwnProperty()` method with `for...of` loop: This approach uses the `hasOwnProperty()` method to check if a property belongs to the object, and then iterates over the object's properties using a `for...of` loop.

**Pros and Cons of Each Approach**

1. `for-in` loop:
	* Pros: Simple and widely supported.
	* Cons: Not as efficient as other methods, can iterate over inherited properties, and may not work well with modern JavaScript features.
2. `Object.keys()` method with `for...of` loop:
	* Pros: Efficient and modern approach.
	* Cons: Requires the `Object.keys()` method, which may not be supported in older browsers or environments.
3. `includes()` method with `for...of` loop:
	* Pros: Modern and efficient approach.
	* Cons: Not supported in older browsers or environments that don't have the `includes()` method.
4. `hasOwnProperty()` method with `for...of` loop:
	* Pros: Efficient and modern approach.
	* Cons: Requires the `hasOwnProperty()` method, which may not be supported in older browsers or environments.

**Library Used**

None of these approaches rely on a specific library. However, if we look at the `Object.keys()` method and its variants (e.g., `includes()`), they are built-in methods provided by modern JavaScript implementations.

**Special JS Features/Syntax**

This benchmark does not use any special or experimental JavaScript features, such as async/await, generators, or ES6+ modules.

**Other Alternatives**

If you're looking for alternative ways to iterate over object properties, you might consider:

* Using a `for...in` loop with the `Object.getOwnPropertyNames()` method.
* Using an array of keys and iterating over it using a traditional `for` loop.
* Using a library like Lodash or Ramda, which provide functions for working with objects.

Keep in mind that each approach has its own trade-offs, and the best choice depends on your specific use case and requirements.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.107 Safari/537.36

Browser/OS: Chrome 92 on Windows

View result in a separate tab

Test name	Executions per second
for-in	143.1 Ops/sec
for-of Object.keys	114.3 Ops/sec
for-of Object.keys includes	412.4 Ops/sec
for-of Object.keys hasOwnProperty	32.4 Ops/sec

Related benchmarks:

for-in vs for-of Object.keys 2 (version: 6)

Comparing performance of: for-in vs for-of Object.keys vs for-of Object.keys includes vs for-of Object.keys hasOwnProperty

Created: 3 years ago by: Registered User

Jump to the latest result

for-in

for-of Object.keys

for-of Object.keys includes

for-of Object.keys hasOwnProperty

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):