Benchmark: Set has vs prop in object

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]
'sausage' in obj
Set.has
set.has('saudage')
Object.hasOwnProperty
obj.hasOwnProperty('sausage')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36 Edg/134.0.0.0

Browser/OS: Chrome 134 on Windows

View result in a separate tab

Test name	Executions per second
Includes	120379384.0 Ops/sec
Object[key]	92248600.0 Ops/sec
Set.has	181424480.0 Ops/sec
Object.hasOwnProperty	71172752.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested, compared, and the pros/cons of each approach.

**Benchmark Overview**

The benchmark compares four different ways to check if an array contains a value:

1. `array.includes('sausage')`
2. `'sausage' in obj` (using the `in` operator on an object)
3. `set.has('saudage')` (using a Set data structure)
4. `obj.hasOwnProperty('sausage')`

**Options Compared**

Here's what's being compared:

* `array.includes()`: checks if the array includes the specified value.
* `in` Operator: checks if the object has a property with the specified key.
* Set (`set.has()`) data structure: contains unique values and provides fast membership testing.

**Pros/Cons of Each Approach**

1. **Array Includes**: This method is convenient, but it can be slow for large arrays because it needs to iterate through the entire array. However, for small arrays, it's usually fast enough.
	* Pros: easy to use, no need for additional data structures or complex logic.
	* Cons: can be slow for large arrays, may not be optimized for performance.
2. **`in` Operator**: This method is faster than `array.includes()` because it uses a hash table lookup. However, it requires an object and may be slower if the object is very large or has many properties.
	* Pros: fast, convenient when working with objects.
	* Cons: requires an object, may not work well for arrays or very large objects.
3. **Set (`set.has()`) data structure**: This method is optimized for fast membership testing and provides good performance for checking if a value is present in the set.
	* Pros: fast, efficient, easy to use with sets.
	* Cons: requires additional data structure (Set) and may not be necessary for small arrays or simple checks.

**Library Used**

None of these methods rely on any specific libraries beyond JavaScript's built-in features. However, the `in` operator uses a hash table lookup under the hood, which is implemented by the browser's JavaScript engine.

**Special JS Features/Syntax**

The benchmark doesn't use any special JavaScript features or syntax beyond the standard `includes()`, `in` operator, and Set data structure.

**Other Alternatives**

For arrays, other alternatives to `array.includes()` could be:

* Using a binary search algorithm (e.g., `array.binarySearch()`).
* Creating an index or map of array elements for fast lookup.

For objects, other alternatives to the `in` operator could be:

* Using `Object.keys()` and iterating through the resulting array.
* Creating a map of object properties for fast lookup.

For sets, other alternatives to `set.has()` could be:

* Using a different data structure like a balanced binary search tree or a heap.

Keep in mind that these alternatives may not provide better performance for specific use cases and might even introduce additional complexity.

Related benchmarks:

Set has vs prop in object (version: 0)

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

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

Created: one year ago by: Guest

Jump to the latest result

Includes

Object[key]

Set.has

Object.hasOwnProperty

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):