Benchmark: Set has vs object key

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
set.has('saudage')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

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

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 4 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:146.0) Gecko/20100101 Firefox/146.0

Browser/OS: Firefox 146 on Windows

View result in a separate tab

Test name	Executions per second
Includes	24313642.0 Ops/sec
Object[key]	751150784.0 Ops/sec
Set.has	755223808.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark and explain what's being tested.

**Benchmark Definition JSON**

The benchmark definition represents three different ways to check if an array contains a specific value:

1. `Set.has('sausage')`: This method checks if a Set object contains the string 'sausage'. A Set is an unordered collection of unique values.
2. `obj['sausage']`: This method accesses the property 'sausage' on the `obj` object, which is created by reducing an array with null values and adding random keys. This approach relies on object key lookups.
3. `array.includes('sausage')`: This method checks if the string 'sausage' exists in the `array`. The array contains a large number of unique random strings.

**Options Compared**

The benchmark compares three different approaches:

* **Set.has**: Using a Set data structure to check for membership. Sets are optimized for fast lookups and have an average time complexity of O(1).
* **Object[key]**: Accessing the property on the object using bracket notation (`obj['sausage']`). This approach relies on object key lookups, which can be slower than using a Set.
* **includes()**: Using the `array.includes()` method to check for membership in the array. This approach is generally faster than accessing individual elements of the array.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Set.has**:
	+ Pros: Fast lookups, optimized for membership checks.
	+ Cons: May not work as expected with non-unique values or objects that have duplicate keys.
* **Object[key]**:
	+ Pros: Works well with objects that have unique keys.
	+ Cons: Can be slower than Set.has due to the overhead of property access and potential cache misses.
* **includes()**:
	+ Pros: Fast, efficient way to check for membership in arrays.
	+ Cons: May not work as expected if the array contains non-unique values or is very large.

**Library and Special JS Features**

The benchmark uses a JavaScript library called YaBrowser/24 (Yandex Browser), which provides a specific implementation of WebKit-based browsing. There are no special JS features mentioned in this benchmark, so I won't discuss any further.

**Other Alternatives**

If you're looking for alternative ways to check if an array contains a value, you could consider using:

* **Arrays.indexOf()**: This method returns the index of the first occurrence of the specified value. If the value is not found, it returns -1.
* **Arrays.includes() with spread operator**: You can use the spread operator (`[...array].includes()` to check if an array contains a value.

Keep in mind that these alternatives may have different performance characteristics and are not necessarily more efficient than the methods being compared in this benchmark.

Related benchmarks:

Set has vs object key (version: 0)

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

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

Created: 4 years ago by: Guest

Jump to the latest result

Includes

Object[key]

Set.has

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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