Benchmark: Hashmap.has vs Array.Filter (random access - generated at start)

Script Preparation code:

const counter = 10000
const map = new Map()
const array = new Array(counter)
let randomIndex = getRandomInt(counter)

window.counter = counter
window.map = map
window.array = array
for (let i = 0; i < counter; i++) {
    map.set(i)
    array[i] = i
}

function getRandomInt(max) {
  	return Math.floor(Math.random() * max);
}

Tests:

Hashmap
window.map.has(randomIndex)
Array.filter
window.array.filter((value) => value === randomIndex)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Hashmap
Array.filter

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

Test name	Executions per second
Hashmap	158471312.0 Ops/sec
Array.filter	62992.8 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The provided benchmark assesses the performance of two different approaches for checking the presence of an element in a collection: using a **JavaScript `Map`** with the `has` method versus using an **Array** with the `filter` method. Here’s a breakdown of the benchmark, including what is being tested, the options compared, pros and cons of each approach, and alternative solutions.

### Benchmark Overview

1. **Tested Options**:
   - **Hashmap (Map)**: `window.map.has(randomIndex)`
   - **Array Filter**: `window.array.filter((value) => value === randomIndex)`

2. **Preparation Code**:
   - A `Map` and an `Array` are both populated with 10,000 elements (from 0 to 9,999).
   - After the collections are prepared, a random index is selected to test the presence of that index in both the `Map` and the `Array`.

### Pros and Cons of Each Approach

#### 1. Hashmap (Map)

- **Pros**:
  - The `has` method for `Map` checks for the presence of a key efficiently, typically in constant time \(O(1)\). This is because `Map` is optimized for key-value pairs and allows for fast lookups.
  - The `Map` structure inherently allows for unique keys.
  
- **Cons**:
  - Requires more memory than a simple Array to store key-value pairs.
  - If the only need is to store sequential numbers, it might be an overhead compared to an Array.

#### 2. Array Filter

- **Pros**:
  - Arrays are simple and easy to work with; they offer a straightforward way to hold and iterate over a list of values.
  - Higher compatibility with functional programming styles as they allow the use of methods like `filter`.
  
- **Cons**:
  - The `filter` method creates a new array with all elements that pass the test implemented by the provided function, leading to potential waste of memory and time, especially when checking for a single element. Specifically, the time complexity for this approach is \(O(n)\) in the worst case, as it may need to examine every element in the array.
  - Performing an equality check for each element can be slower and less efficient than direct key presence checking.

### Additional Considerations

- **Use Cases**: The choice between using a `Map` versus an `Array` should be driven by the specific performance needs and usage patterns. If frequent presence checks are necessary, the `Map` is likely the better choice, whereas for relatively small datasets where order and index access matter, an Array may suffice.
  
- **Alternatives**:
  - **Set**: If your use case is limited to unique values, a `Set` could be a good alternative. It provides an efficient way to check for existence (similar to `Map`) but without the need for key-value pairs.
  - **Object**: For a simple key-value pair usage, JavaScript objects (`{}` syntax) can be used, but they lack some features of `Map`, such as maintaining the order of keys.

### Conclusion

This benchmark shows a clear performance difference between the two methods tested: the `Map` implementation (`window.map.has`) is significantly faster than the array filter implementation (`window.array.filter`). By understanding the characteristics of the data structures being used, developers can make informed choices based on performance, memory usage, and programming style preferences for their applications.

Related benchmarks:

Hashmap.has vs Array.Filter (random access - generated at start) (version: 2)

Comparing performance of: Hashmap vs Array.filter

Created: one year ago by: Registered User

Jump to the latest result

Hashmap

Array.filter

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):