Benchmark: set.has vs. array.includes on 25 000 items

Script Preparation code:

var a = Array(25000).fill(0).map((_,i) => i+=1)
var b = new Set(a)

Tests:

includes
return a.includes(23250)
lookup
return b.has(23250)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
includes
lookup

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/111.0.0.0 Safari/537.36

Browser/OS: Chrome 111 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
includes	18441104.0 Ops/sec
lookup	28826792.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided JSON and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark is focused on comparing two approaches:

1. `array.includes()` (also known as "slice-based lookup")
2. `Set.has()` (a built-in JavaScript method for checking membership in a Set data structure)

**Script Preparation Code**
```javascript
var a = Array(25000).fill(0).map((_,i) => i+=1)
var b = new Set(a)
```
This code creates an array `a` with 25,000 elements and fills them with values starting from 1 (since `i += 1`). It then creates a new Set `b` containing the same elements.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark only tests the JavaScript performance of these two approaches.

**Options Compared**

The two options being compared are:

1. **Slice-based lookup (`array.includes()`):** This approach searches for a value in an array by iterating over the elements until it finds a match or reaches the end of the array.
2. **Set membership check (`Set.has()`):** This approach uses a data structure (a Set) to store unique values and checks if a value is present in the Set.

**Pros and Cons**

**Slice-based lookup (`array.includes()`):**

Pros:

* Widely supported by most browsers
* Can be used with arrays of any size
* Can be optimized for performance

Cons:

* Iterates over all elements, which can be slow for large datasets
* May involve bounds checking (e.g., when searching within a range)

**Set membership check (`Set.has()`):**

Pros:

* O(1) lookup time on average, making it much faster than slice-based lookup for large datasets
* Efficient use of memory

Cons:

* Not all browsers support Set objects or the `has()` method
* Requires creating and populating a Set with unique values (as in this benchmark)

**Other Considerations**

In general, when dealing with arrays, `slice-based lookup` might be preferred for smaller datasets due to its simplicity. However, as the dataset grows, `Set membership check` becomes more efficient.

It's also worth noting that Sets are designed for fast lookups and insertion/removal operations, making them suitable for applications where data is frequently added or removed. In contrast, arrays are optimized for sequential access and manipulation.

**Library or Framework**

None explicitly mentioned in the benchmark definition.

**Special JS Feature or Syntax**

The `Map` object and the `Set` object are being used here to demonstrate the performance difference between these two approaches. Both of these data structures are built-in JavaScript objects that provide efficient lookup, insertion, and deletion operations.

In the context of this benchmark, using a Set (`b`) is crucial for achieving the expected O(1) lookup time. Without it, the comparison would not be fair or meaningful.

If you're interested in exploring other JavaScript features, I can discuss some alternatives, such as:

* Using `Map` objects instead of Sets
* Comparing different array methods (e.g., `indexOf()`, `findIndex()`)
* Testing browser-specific optimizations (e.g., WebAssembly)

Feel free to ask if you'd like me to elaborate on any of these points!

Related benchmarks:

set.has vs. array.includes on 25 000 items (version: 0)

Comparing performance of: includes vs lookup

Created: one year ago by: Guest

Jump to the latest result

includes

lookup

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):