Benchmark: array includes vs object key vs set

Script Preparation code:

var obj = (new Array(1000)).fill(null).reduce((prev, newVal) => {prev[Math.random() + ''] = Math.random() + ''; return prev; }, { sausage: 'tst' });
var array = Object.keys(obj);
var set = new Set(array);

Tests:

Includes
array.includes('sausage')
Object[key]
obj['sausage']
Set.has(key)
set.has('sausage')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Includes
Object[key]
Set.has(key)

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its test cases.

**Benchmark Definition JSON**

The provided JSON defines a benchmark that compares the performance of three different approaches to check if an array contains a value:

1. `array.includes('sausage')`
2. `obj['sausage']` (using object key lookup)
3. `set.has('sausage')` (using a Set data structure)

**Script Preparation Code**

The script preparation code creates a large object (`obj`) with 1000 properties, where each property has a random key and value. The keys are stored in an array (`array`), which is then converted to a Set (`set`). This setup ensures that the benchmark focuses on the performance of these specific operations.

**Options Compared**

The three test cases compare the following options:

* `includes`: checks if a value exists in an array using the `includes` method.
* `Object[key]`: uses object key lookup to access a property by its string representation (in this case, `'sausage'`).
* `Set.has(key)`: uses the `has` method of a Set data structure to check if a key is present.

**Pros and Cons**

Here's a brief summary of each approach:

1. **`array.includes('sausage')`**:
	* Pros: Simple, widely supported, and relatively fast.
	* Cons: May perform a linear search on the array, which can be slow for large arrays.
2. **`obj['sausage']` (Object Key Lookup)**:
	* Pros: Fast, as it uses direct property access, but may require more memory to store the object.
	* Cons: Only works if the property name is a string literal; attempting to use a variable or expression will result in a syntax error.
3. **`set.has('sausage')` (Set Data Structure)**:
	* Pros: Fast and efficient, as Sets are optimized for membership testing.
	* Cons: May require additional memory to store the Set, and may not be suitable for large datasets.

**Library/Functionality Used**

None of these test cases use a specific library or framework. However, it's worth noting that the `includes` method is a built-in method in JavaScript arrays, so no external library is required.

**Special JS Features/Syntax**

There are no special JS features or syntax used in this benchmark. All three approaches rely on standard JavaScript language constructs.

**Other Alternatives**

For larger datasets or more complex scenarios, alternative approaches might include:

1. **Regular expressions**: Using a regular expression to search for the value can be faster than `includes` for large arrays.
2. **Index-based lookup**: If the array is sorted or has an index, using an index-based lookup (e.g., binary search) can be more efficient than `includes`.
3. **Native methods**: Depending on the browser and JavaScript engine, native methods like `Array.prototype.find()` or `Set.prototype.has()` might be available for even faster performance.

Keep in mind that the specific approach chosen will depend on the use case and requirements of the application.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
Includes	15497112.0 Ops/sec
Object[key]	14744717.0 Ops/sec
Set.has(key)	15518599.0 Ops/sec

Related benchmarks:

array includes vs object key vs set (version: 0)

performance comparison of ways to find if an array contains a value

Comparing performance of: Includes vs Object[key] vs Set.has(key)

Created: 7 months ago by: Guest

Jump to the latest result

Includes

Object[key]

Set.has(key)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):