Benchmark: Object.keys vs for...in

Script Preparation code:

var users = {
  user1: {
    name: "John1",
    age: 30
  },
  user2: {
    name: "John2",
    age: 20
  },
  user3: {
    name: "John3",
    age: 25
  },
  user4: {
    name: "John4",
    age: 50
  }
};

Tests:

Object.keys
Object.keys(users).forEach(userId => console.log(users[userId]));
for...in
for (const userId in users) { if (users.hasOwnProperty(userId)) { console.log(users[userId]) } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.keys
for...in

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the benchmark.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark test case on MeasureThat.net. The test measures the performance difference between two approaches:

1. `Object.keys()`: This method returns an array of strings representing the keys of the given object.
2. `for...in` loop: This loop iterates over the properties (keys) of an object.

**Options compared**

The benchmark compares the execution speed of these two options in different scenarios, specifically:

* Accessing individual object values using `Object.keys()` vs `for...in`
* Iterating over all object keys without filtering (`Object.keys()`) vs using a `for...in` loop with `hasOwnProperty()` to filter out non-enumerable properties

**Pros and cons of each approach**

1. `Object.keys()`:
	* Pros: Fast, efficient, and widely supported.
	* Cons: Only returns enumerable keys, may not work well with non-enumerable properties or symbols.
2. `for...in` loop:
	* Pros: Can handle all properties (enumerable and non-enumerable), can be more flexible when working with objects.
	* Cons: Slower than `Object.keys()`, may have performance issues due to the overhead of iterating over properties.

**Library usage**

In this benchmark, the `console.log()` function is used for output. This is a built-in JavaScript function and not a library-specific implementation.

**Special JS features or syntax**

There are no notable special JS features or syntax used in this benchmark. The code primarily uses standard JavaScript concepts and methods.

**Other alternatives**

For similar benchmarks or scenarios, consider the following alternatives:

* Using `Array.from()` to iterate over an array of keys instead of `Object.keys()`
* Utilizing modern JavaScript features like `for...of` loops for iterating over arrays or objects
* Leveraging libraries like Lodash or Ramda for utility functions that might improve performance in specific scenarios

Keep in mind that these alternatives may not necessarily provide a significant performance boost, and the choice of approach depends on the specific requirements and constraints of your project.

Related benchmarks:

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

Comparing performance of: Object.keys vs for...in

Created: 5 years ago by: Guest

Jump to the latest result

Object.keys

for...in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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