Benchmark: array.includes vs set.has on 100 elements

HTML Preparation code:

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

Script Preparation code:

const arr = [];
const elementsCount = 100;
for (let i = 0; i < elementsCount; i++) {
	arr.push(i);
};
const set = new Set(arr);

Tests:

array.includes
for (let i = 0; i < elementsCount; i++) { arr.includes(i); };
set.has
for (let i = 0; i < elementsCount; i++) { set.has(i); };

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array.includes
set.has

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:146.0) Gecko/20100101 Firefox/146.0

Browser/OS: Firefox 146 on Mac OS X 10.15

View result in a separate tab

set.has

19.9M/s

array.includes

172K/s

View exact numbers

Test name	Executions per second
✓ set.has	19,907,282 Ops/sec
array.includes	172,310 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark described tests the performance of two different approaches for checking the existence of elements in a collection: using the `Array.prototype.includes` method compared to using the `Set.prototype.has` method. Both methods are utilized on a collection consisting of 100 elements, and each element is checked once.

### Benchmark Details

**1. Options Being Compared:**
   - **`array.includes`**: This method is called on an array, and it checks if a specified value is present in the array.
   - **`set.has`**: This method is called on a Set, a data structure that stores unique values, and it checks if a specified value exists in the Set.

**2. Pros and Cons of Each Approach:**

- **`array.includes`**:
  - **Pros**:
    - Simplicity: Easy to understand and use when working with arrays directly.
    - Well-integrated with array methods, making it a natural choice for list-like structures.
  - **Cons**:
    - Performance: The method has to iterate through the array to check for the presence of the element, leading to a time complexity of O(n) in the worst case (where n is the number of elements in the array).
  
- **`set.has`**:
  - **Pros**:
    - Performance: Checking for the presence of an element in a Set is optimized; it generally has a time complexity of O(1) in average scenarios, due to its underlying hash-based structure.
    - Uniqueness: Automatically enforces unique values, eliminating the need to worry about duplicates.
  - **Cons**:
    - Overhead: There is a slight overhead in creating a Set, especially if you're converting an existing array into a Set.
    - Not suitable for ordered collections if the order of elements is important, as Sets are inherently unordered.

### Other Considerations
- **Memory Usage**: A Set may use more memory than an array since it has to keep track of unique elements independently.
- **Use Cases**: `array.includes` is beneficial if the order of elements and array-specific operations are necessary. In contrast, `set.has` is a preferred solution when the primary requirement is fast membership checking without concern for element order or duplicates.

### Benchmark Results
In the provided benchmark results, we observe that the `set.has` method executed significantly more times per second (approximately 4.55 million) compared to the `array.includes` method (approximately 694 thousand). This reflects the efficiency advantage of using Sets for membership checking.

### Alternatives
Other alternatives for checking membership include:

- **Using a Map**: Similar to Sets, Maps can also provide O(1) average time complexity for existence checks when looking for keys.
- **Basic Looping**: A simple `for` loop can run through the array, but this will have a performance cost similar to `array.includes`.
- **IndexOf or Find**: Older methods like `array.indexOf` or `array.find` offer similar functionality but are less semantically clear for checking inclusion.

In conclusion, the benchmark demonstrates the clear performance advantages of using `set.has` over `array.includes` for membership checking in JavaScript, particularly in large collections or scenarios where performance is critical.

array.includes vs set.has on 100 elements (version: 1)

100 elements and each element check once

Comparing performance of: `array.includes vs set.has`

Created: one year ago by: Registered User

Go to the latest result

array.includes

set.has

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

array.includes vs set.has on 100 elements (version: 1)

100 elements and each element check once

Comparing performance of: array.includes vs set.has

Created: one year ago by: Registered User

Go to the latest result

array.includes

set.has

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

Related benchmarks

Comparing performance of: `array.includes vs set.has`