Benchmark: Array.includes vs Dictionary lookup

HTML Preparation code:

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

Script Preparation code:

var myArr = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'];
var myDict = _.keyBy(myArr);

Tests:

Array.includes
if (myArr.includes('m')) { console.log("array has 'm'"); }
Dictionary lookup
if (myDict['m']) { console.log("dict has 'm'"); }

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Array.includes

336K/s

Dictionary lookup

327K/s

View exact numbers

✓ Array.includes: 336,139 ops/sec
• Dictionary lookup: 327,352 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
Array.includes
Dictionary lookup

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/139.0.0.0 Safari/537.36 Edg/139.0.0.0

Browser/OS: Chrome 139 on Windows

View result in a separate tab

Dictionary lookup

505K/s

Array.includes

480K/s

View exact numbers

Test name	Executions per second
✓ Dictionary lookup	504,612 Ops/sec
Array.includes	480,324 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 benchmark and its components.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches: using `Array.includes()` to search for an element in an array, and using dictionary (object) lookup to achieve the same result. The benchmark aims to determine which approach is faster.

**Options compared:**

1. **Array.includes()**: This method searches for an element in the array and returns a boolean value indicating whether the element exists.
2. **Dictionary lookup**: This method uses an object to store key-value pairs, where each key corresponds to a specific element in the original array. The benchmark uses Lodash's `_.keyBy()` function to create this dictionary.

**Pros and Cons:**

* **Array.includes()**:
	+ Pros:
		- Easy to understand and implement.
		- Widely supported across browsers.
	+ Cons:
		- Can be slower due to the linear search algorithm used by default (although some modern browsers optimize it).
* **Dictionary lookup**:
	+ Pros:
		- Generally faster, especially for larger datasets, since it uses a hash table-based search.
	+ Cons:
		- Requires creating an additional object and potentially more memory usage.

The choice between these two approaches depends on the specific use case and performance requirements. If speed is critical, dictionary lookup might be a better option. However, if simplicity and ease of implementation are prioritized, `Array.includes()` could be sufficient.

**Library used:**

* **Lodash**: The benchmark uses Lodash's `_.keyBy()` function to create the dictionary. Lodash is a popular JavaScript library that provides a collection of functional programming helpers and utility functions.

**Special JS feature or syntax:**

The benchmark does not use any special JavaScript features or syntax beyond what's standard in modern JavaScript.

**Other alternatives:**

If you're looking for alternative approaches, consider the following:

1. **Splice()**: Instead of using `Array.includes()` or dictionary lookup, you could use `splice()` to find and remove the element from the array.
2. **Set data structure**: If you need to frequently search for elements in an array, consider converting it to a Set data structure, which provides faster lookups.

Keep in mind that these alternatives might have different trade-offs in terms of memory usage, complexity, and performance compared to the original approaches used in the benchmark.

Array.includes vs Dictionary lookup (version: 0)

Comparing performance of: `Array.includes vs Dictionary lookup`

Created: 6 years ago by: Guest

Go to the latest result

Array.includes

Dictionary lookup

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Array.includes vs Dictionary lookup (version: 0)

Comparing performance of: Array.includes vs Dictionary lookup

Created: 6 years ago by: Guest

Go to the latest result

Array.includes

Dictionary lookup

Historical Performance Data aggregated from 12 community runs

Desktop Results:

Chrome 12 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Comparing performance of: `Array.includes vs Dictionary lookup`