Benchmark: index vs map112 - MeasureThat.net

Script Preparation code:

var myArray = [];
for (let i = 0; i < 99; i++) {
	myArray.push(i)
}

Tests:

1
var unique = myArray.filter((value, index, array) => array.indexOf(value) === index);
2
let map = {}; myArray.forEach(v => { map[v]=true }) Object.keys(map);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
1
2

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/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Windows

View result in a separate tab

Test name	Executions per second
1	523272.9 Ops/sec
2	485493.6 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll explain the benchmark in a way that's easy to understand, even for those without deep knowledge of JavaScript.

**What is being tested?**

The provided JSON represents two different microbenchmarks being run on MeasureThat.net:

1. The first test case uses the `filter()` method to create an array containing only unique values from the original array.
2. The second test case uses a Map data structure (introduced in ECMAScript 2015) to count the occurrences of each value in the original array.

**Options compared**

The two approaches being tested are:

1. **`filter()` method**: This method iterates over the array and checks for each element if it appears only once by verifying its index against the `indexOf()` method's result.
2. **Map data structure**: This approach creates a Map where each key is an element from the original array, and its value is set to true. Then, it uses `Object.keys()` to get an array of keys, which represents the unique elements.

**Pros and cons of each approach**

1. **`filter()` method**:
	* Pros:
		+ Simple and easy to understand.
		+ Does not require creating any additional data structures (like a Map).
	* Cons:
		+ It has a higher constant factor due to the `indexOf()` method's time complexity, making it slower for large datasets.
2. **Map data structure**:
	* Pros:
		+ Can be faster than the `filter()` method because it uses a hash table (Map) for lookups, which is typically O(1) time complexity.
	* Cons:
		+ Requires creating an additional data structure (the Map), which can have overhead in terms of memory allocation and garbage collection.

**Other considerations**

Both approaches have different strengths and weaknesses. The `filter()` method is more intuitive but may be slower due to the `indexOf()` method's time complexity. The Map approach is faster but requires understanding of a new data structure.

**Library used**

In this benchmark, no specific library is required beyond what comes with JavaScript (ECMAScript standard). However, it's worth noting that modern browsers have implemented various polyfills for older ECMAScript features to ensure compatibility.

**Special JS feature/syntax**

The `Map` data structure was introduced in ECMAScript 2015. While the benchmark uses a simplified example, it demonstrates the basics of using a Map for fast lookups.

In summary, this benchmark tests two approaches to finding unique elements in an array: one using the `filter()` method and another using a Map data structure. Each approach has its strengths and weaknesses, and understanding these differences can help developers optimize their code for specific use cases.

Related benchmarks:

index vs map112 (version: 0)

Comparing performance of: 1 vs 2

Created: one year ago by: Guest

Jump to the latest result

1

2

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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