Benchmark: map foreach vs array lookup

Script Preparation code:

var arr = [];
var map = new Map();

for (let i = 0; i < 12000; i++) {
  const num = i * 7 + Math.ceil(Math.random() * 5); 
  const str = (Math.random() + 1).toString(36).substring(7);
  arr.push(num);
  map.set(num, str);
}

Tests:

arr to map lookup
for (let i = 0;i < arr.length; i++) { let num = arr[i]; let str = map.get(num) || ''; }
map foreach
map.forEach((el)=>{})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
arr to map lookup
map foreach

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares two approaches for iterating over an array when you need to look up values in a Map (a built-in JavaScript data structure). The tests aim to measure which approach is faster, more efficient, or both.

**Approaches Compared**

There are two main approaches compared:

1. **Direct Array Lookup**: This involves using the `map.get()` method to directly access the value associated with each key in the array.
2. **Map.forEach()**: This involves using the `forEach` method on the Map object to iterate over its entries.

**Pros and Cons**

**Direct Array Lookup (arr to map lookup)**

Pros:

* More explicit and readable code
* Can be more efficient if you know exactly which key to look up
* No unnecessary overhead from iterating over all keys in the Map

Cons:

* Requires more manual work to set up the lookup
* May not be as scalable or performant for large datasets

**Map.forEach() (map foreach)**

Pros:

* Simplifies the code and makes it easier to read
* Can be more efficient when dealing with large datasets, since `forEach` will only iterate over keys that are actually present in the Map
* Less manual work required compared to direct array lookup

Cons:

* May have unnecessary overhead due to iteration over all keys in the Map
* Can be less readable if not used carefully

**Library Usage**

The benchmark uses the built-in JavaScript `Map` object, which is a simple key-value store that allows you to look up values by their corresponding keys.

**Special JavaScript Features/Syntax**

There are no special JavaScript features or syntax mentioned in the benchmark. It's purely focused on comparing two approaches for iterating over an array when using a Map.

**Other Alternatives**

Other alternatives to consider when dealing with arrays and Maps include:

* Using `Object.keys()` or `Array.prototype.forEach()` to iterate over keys, instead of directly accessing them through the `map.get()` method
* Using other data structures like Sets or Objects to store and look up values
* Optimizing the code for specific use cases, such as using caching or memoization techniques

I hope this explanation helps!

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.20 Safari/537.36

Browser/OS: Chrome 94 on Linux

View result in a separate tab

Test name	Executions per second
arr to map lookup	427.2 Ops/sec
map foreach	10528.4 Ops/sec

Related benchmarks:

map foreach vs array lookup (version: 0)

Comparing performance of: arr to map lookup vs map foreach

Created: 3 years ago by: Guest

Jump to the latest result

arr to map lookup

map foreach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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