Benchmark: set.has vs. array.includes vs obj[key] vs map.get

Script Preparation code:

var a = Array(10000).fill(undefined).map((_, i) => i);
var b = a.reduce((acc, el) => { acc[el] = true; return acc }, {});
var c = new Set(a);
var d = new Map(a.map(el => [el, true]));

Tests:

includes
return a.includes(9)
hash
return b['9']
set
return c.has(9)
map
return d.get(9)

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

hash

34.0M/s

set

33.3M/s

includes

32.9M/s

map

32.0M/s

View exact numbers

✓ hash: 33,953,868 ops/sec
• set: 33,319,178 ops/sec
• includes: 32,919,978 ops/sec
• map: 32,044,680 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
includes
hash
set
map

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Windows

View result in a separate tab

set

45.4M/s

hash

44.1M/s

map

43.8M/s

includes

25.7M/s

View exact numbers

Test name	Executions per second
✓ set	45,429,340 Ops/sec
hash	44,145,224 Ops/sec
map	43,847,180 Ops/sec
includes	25,697,368 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark json and explain what is being tested, compared, and its pros and cons.

**Benchmark Definition**

The benchmark definition represents four different ways to check if a value (in this case, 9) exists in an array:

1. `a.includes(9)`: Checks if the array `a` contains the value 9 using the `includes()` method.
2. `b['9']`: Accesses the value associated with key 9 in the object `b`.
3. `c.has(9)`: Checks if the set `c` contains the value 9 using the `has()` method.
4. `d.get(9)`: Retrieves the value associated with key 9 in the map `d`.

**Comparison**

These four methods are being compared to determine which one is the fastest.

**Pros and Cons of each approach:**

1. **`a.includes(9)`**:
	* Pros: Simple, widely supported, and efficient for large arrays.
	* Cons: May be slower than other approaches if the array has many unique elements.
2. **`b['9']`**:
	* Pros: Fast and efficient for small objects with a limited number of keys.
	* Cons: Can be slow for large objects or when using a hash table-like data structure (like `Map`).
3. **`c.has(9)`**:
	* Pros: Efficient for sets, which are optimized for fast membership testing.
	* Cons: May not be as efficient as other approaches for arrays without duplicates.
4. **`d.get(9)`**:
	* Pros: Fast and efficient for maps, which are optimized for fast key lookups.
	* Cons: May not be as efficient as other approaches for objects with a large number of keys.

**Special JS feature or syntax:**

None of the provided methods use special JavaScript features or syntax that would require additional explanation.

**Alternative approaches:**

Other alternatives to these methods could include:

1. Using `Array.prototype.indexOf()` instead of `includes()`.
2. Using a custom loop or function to iterate over the array or object.
3. Using a more specialized data structure, such as a trie or suffix tree, for fast membership testing.

However, these alternative approaches are not being tested in this benchmark.

**Other considerations:**

1. The benchmark is running on a desktop environment with Chrome 125 and Mac OS X 10.15.7.
2. The test cases are designed to be representative of real-world use cases, but the results may vary depending on the specific requirements of your application.
3. It's worth noting that the `Map` implementation in JavaScript is still evolving and may not be optimized for all use cases.

I hope this explanation helps! Let me know if you have any further questions.

set.has vs. array.includes vs obj[key] vs map.get (version: 0)

Comparing performance of: `includes vs hash vs set vs map`

Created: 4 years ago by: Guest

Go to the latest result

includes

hash

set

map

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

set.has vs. array.includes vs obj[key] vs map.get (version: 0)

Comparing performance of: includes vs hash vs set vs map

Created: 4 years ago by: Guest

Go to the latest result

includes

hash

set

map

Historical Performance Data aggregated from 5 community runs

Desktop Results:

Chrome 5 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `includes vs hash vs set vs map`