Benchmark: Object iteration vs Map iteration 123

Script Preparation code:

var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6,
  g: 7,
  h: 8,
  i: 9,
  j: 10,
  k: 11,
  l: 12,
  m: 13,
  n: 14,
  o: 15,
  p: 16,
  q: 17,
  r: 18,
  s: 19,
  t: 20,
  u: 21,
  v: 22,
  w: 23,
  x: 24,
  y: 25,
  z: 26
};
var map = new Map(Object.entries(obj));
var arr = Object.values(obj);

Tests:

array
let a = 0; arr.forEach((v) => { a += v; });
map
let a = 0; map.forEach((v, k) => { a += v; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
array
map

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Android 14; Mobile; rv:138.0) Gecko/138.0 Firefox/138.0

Browser/OS: Firefox Mobile 138 on Android

View result in a separate tab

array

2.9M/s

map

2.8M/s

View exact numbers

Test name	Executions per second
✓ array	2,943,494 Ops/sec
map	2,844,834 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what is tested in the provided JSON, comparing different options and their pros and cons.

**Benchmark Definition**

The benchmark measures the performance of iterating over an array versus using a Map to iterate over the same data.

**Options Compared**

There are two main options compared:

1. **Array Iteration**: Using `arr.forEach()` to iterate over the array.
2. **Map Iteration**: Using `map.forEach()` to iterate over the Map.

**Pros and Cons of Each Approach**

### Array Iteration (`arr.forEach()`)

* Pros:
	+ Wide support across browsers and platforms.
	+ Easy to read and understand, as it's a straightforward iteration process.
* Cons:
	+ Can be slower for large datasets due to the need to access array elements sequentially.

### Map Iteration (`map.forEach()`)

* Pros:
	+ Generally faster than array iteration for large datasets, as it can take advantage of caching and more efficient memory management.
	+ Allows for easy iteration over both key-value pairs (as in this benchmark) and values only.
* Cons:
	+ Less supported across older browsers and platforms, which may be a limitation.

**Library Used**

In the provided JSON, `Object.entries()` is used to create an array of key-value pairs from the original object. This function is part of the ECMAScript standard (ES6+) and is widely supported in modern browsers. It serves as a bridge between the original object and the Map data structure.

**Special JS Feature or Syntax**

In this benchmark, `const` is used to declare variables, which is the default keyword for declaring constant variables in JavaScript, starting from ECMAScript 2015 (ES6). This syntax is widely supported across browsers and platforms.

**Other Considerations**

* **Browser Support**: The benchmark uses Chrome 116 on a Mac OS X 10.15.7 platform. Other browsers may not support Map iteration or have different performance characteristics.
* **Hardware and Software Configuration**: The benchmark's results are affected by the hardware and software configuration of the test device. This includes factors like processor speed, memory allocation, and caching.

**Alternatives**

If you need to compare other iteration methods, consider these alternatives:

1. **Array.prototype.forEach.call()**: Similar to `arr.forEach()`, but uses a more traditional, non-async approach.
2. **Array.prototype.map()**: Iterates over the array using a callback function, which can be useful for transforming data.
3. **Set Iteration**: If you need to iterate over unique values only, consider using a Set and iterating over its `values()` method.

Keep in mind that these alternatives might have different performance characteristics or limitations compared to the original array iteration approach used in this benchmark.

Object iteration vs Map iteration 123 (version: 0)

Comparing performance of: `array vs map`

Created: 2 years ago by: Guest

Go to the latest result

array

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Object iteration vs Map iteration 123 (version: 0)

Comparing performance of: array vs map

Created: 2 years ago by: Guest

Go to the latest result

array

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `array vs map`