Benchmark: Array.includes vs Set.has vs Map.has vs Object in

Script Preparation code:

var a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
var b = new Set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
var c = new Map([[1, 1], [2, 2], [3, 3], [4, 4], [5, 5], [6, 6], [7, 7], [8, 8], [9, 9], [10, 10]]);
var d = {1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9, 10: 10};

Tests:

Array includes
return a.includes(9);
Set has
return b.has(9);
Map has
return c.has(9);
object key
return "9" in d

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array includes
Set has
Map has
object key

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 20 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array includes	110344064.0 Ops/sec
Set has	194053648.0 Ops/sec
Map has	192628208.0 Ops/sec
object key	190403408.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**What is being tested?**

The provided benchmark tests the performance of four different approaches for checking if a value exists in an object, array, set, or map:

1. `Array.includes()`
2. `Set.has()`
3. `Map.has()`
4. `object key` (using the "in" operator)

**Options compared**

Each test case compares two approaches: one using the built-in method and another using a direct property access.

**Pros and Cons of each approach:**

1. **Array.includes()**
	* Pros:
		+ Widely supported in modern browsers.
		+ Often optimized for performance.
	* Cons:
		+ May not work as expected with sparse arrays or large arrays.
		+ Can be slower due to iteration over the array elements.
2. **Set.has()**
	* Pros:
		+ Fast lookup times, especially for large sets.
		+ Less prone to errors compared to direct property access.
	* Cons:
		+ Not supported in older browsers (IE 11 and below).
		+ May not work well with non-numeric keys or values.
3. **Map.has()**
	* Pros:
		+ Fast lookup times, similar to Set.has().
		+ Suitable for large maps with many key-value pairs.
	* Cons:
		+ Less supported compared to Sets (not in older browsers).
		+ May not work well with non-numeric keys or values.
4. **object key**
	* Pros:
		+ Widely supported across different browsers and versions.
		+ Often faster than built-in methods for small objects.
	* Cons:
		+ Can be slower for large objects due to property iteration.

**Special JS features or syntax**

None of the tested approaches rely on special JavaScript features like async/await, Promises, or modern JavaScript syntax.

**Library usage**

No libraries are used in these benchmark test cases. However, if you're interested in using a library like Lodash for utility functions, it can impact performance and may not be suitable for microbenchmarking.

**Other considerations**

When choosing an approach, consider the following factors:

* Performance requirements: If speed is crucial, Set.has() or Map.has() might be a better choice.
* Browser support: Make sure to test on different browsers and versions to ensure compatibility.
* Object size: For small objects, object key might be faster than built-in methods. For larger objects, the performance difference may not be noticeable.

**Alternatives**

Other alternatives for checking if a value exists in an object or array include:

1. **Object.prototype.hasOwnProperty.call()**: A more explicit and safer approach.
2. **for...in loop**: Iterating over the object's properties using a for...in loop can also work, but it may not be as efficient.
3. **Array.prototype.findIndex()**: This method returns the index of the first element that satisfies the condition or -1 if no element matches.

Keep in mind that these alternatives might have different performance characteristics and are not always suitable for microbenchmarking.

Related benchmarks:

Array.includes vs Set.has vs Map.has vs Object in (version: 0)

Comparing performance of: Array includes vs Set has vs Map has vs object key

Created: one year ago by: Guest

Jump to the latest result

Array includes

Set has

Map has

object key

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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