Benchmark: array diff (lodash difference / sets / includes) perf

Script Preparation code:

function dec2hex (dec) {
  return dec < 10
    ? '0' + String(dec)
    : dec.toString(16)
}

function generateId (len) {
  var arr = new Uint8Array((len || 40) / 2)
  window.crypto.getRandomValues(arr)
  return Array.from(arr, dec2hex).join('')
}

var a = []
var b = []
for( let i = 0; i < 1000; i++)
{
  a[i] = generateId(16)
  b[i] = generateId(16)
}

Tests:

with Sets
function diff(a, b) { const as = new Set(a); const bs = new Set(b); return Array.from(new Set([...as].filter(x => !bs.has(x)))); }
with filter-includes
const difference = a.filter(x => !b.includes(x));
lodash.difference
_.difference(a, b)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
with Sets
with filter-includes
lodash.difference

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark measures the performance of three different approaches for finding the difference between two arrays in JavaScript: using `Set`, `filter` with `includes`, and Lodash's `difference` function.

**Approaches Compared**

1. **With Sets**: This approach uses a `Set` data structure to store unique elements from each array, and then filters out elements that are present in both sets.
2. **With filter-includes**: This approach uses the `filter` method with the `includes` method to find elements that are not present in the second array.
3. **Lodash.difference**: This approach uses Lodash's built-in `difference` function, which is designed specifically for finding differences between arrays.

**Pros and Cons of Each Approach**

1. **With Sets**:
	* Pros: Simple and efficient, can be faster for large datasets due to the use of a `Set`.
	* Cons: Requires two separate data structures (a `Set` for each array), which can lead to higher memory usage.
2. **With filter-includes**:
	* Pros: Easy to implement and understand, uses existing methods (`filter` and `includes`) that are widely available in JavaScript.
	* Cons: Can be slower than the other approaches due to the overhead of method calls and iterations.
3. **Lodash.difference**:
	* Pros: Highly optimized and designed specifically for this task, can take advantage of parallel processing (in some cases).
	* Cons: Requires Lodash library to be loaded, which adds an extra dependency.

**Library Used**

The `diff` function in the benchmark definition uses a custom implementation that creates two separate sets from each array using `Set`. The actual implementation is:
```javascript
const as = new Set(a);
const bs = new Set(b);

return Array.from(new Set([...as].filter(x => !bs.has(x))));
```
This library is not a standard JavaScript library, but rather a custom implementation designed for this specific benchmark.

**Special JS Feature/Syntax**

None of the approaches used special JavaScript features or syntax. They all rely on basic JavaScript methods and data structures (arrays, `Set`, `filter`).

**Alternatives**

Other alternatives to find differences between two arrays in JavaScript include:

1. Using `indexOf()` method: Find elements that are not present in the second array by checking if an element is not at index `-1` using `indexOf()`.
2. Using a `Map`: Similar to using `Set`, but maps can be useful for more complex data structures or when preserving order matters.
3. Using external libraries: There are many other libraries available that provide optimized implementations of array differences, such as `Array.prototype.diff()` from the `fast-json-stubs` library.

It's worth noting that the performance difference between these approaches may not be significant in all cases, and the choice ultimately depends on the specific requirements and constraints of the project.

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
with Sets	528247168.0 Ops/sec
with filter-includes	145.4 Ops/sec
lodash.difference	7627.5 Ops/sec

Related benchmarks:

array diff (lodash difference / sets / includes) perf (version: 0)

Comparing performance of: with Sets vs with filter-includes vs lodash.difference

Created: 9 months ago by: Registered User

Jump to the latest result

with Sets

with filter-includes

lodash.difference

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):