Benchmark: merge maps - MeasureThat.net

Script Preparation code:

const arr = [];
const arr2 = [];
for (let i = 0; i < 100; i++) {
    arr.push([i, 'Val' + i]);
    arr2.push(['key' + i, 'Val' + i]);
}

var map1 = new Map(arr)
var map2 = new Map(arr2)

Tests:

Merge spread
var map3 = new Map([...map1, ...map2]);
merge foreach
var map4 = new Map(map1) map2.forEach((val, key) => {map4.set(key, val)})
merge 2 foreach
var map4 = new Map() map1.forEach((val, key) => {map4.set(key, val)}) map2.forEach((val, key) => {map4.set(key, val)})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Merge spread
merge foreach
merge 2 foreach

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:136.0) Gecko/20100101 Firefox/136.0

Browser/OS: Firefox 136 on Linux

View result in a separate tab

Test name	Executions per second
Merge spread	128171.4 Ops/sec
merge foreach	197694.5 Ops/sec
merge 2 foreach	211566.0 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 provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to measure the performance of three different approaches for merging two Maps in JavaScript:

1. `merge 2 foreach`
2. `merge foreach`
3. `Merge spread`

**Script Preparation Code**

The script preparation code creates two arrays, `arr` and `arr2`, each containing key-value pairs with a specific structure. The arrays are then used to create two Maps, `map1` and `map2`.

```javascript
const arr = [];
const arr2 = [];

for (let i = 0; i < 100; i++) {
    arr.push([i, 'Val' + i]);
    arr2.push(['key' + i, 'Val' + i]);
}

var map1 = new Map(arr);
var map2 = new Map(arr2);
```

**Html Preparation Code**

There is no HTML preparation code provided for this benchmark.

**Test Cases**

The test cases are defined in the `Benchmark Definition` json field. Each test case has a unique name and a corresponding `Benchmark Definition` string that represents the code to be executed.

```javascript
var map3 = new Map([...map1, ...map2]);
```

This is the `merge 2 foreach` approach. It uses the spread operator (`...`) to merge the two Maps into one.

```javascript
var map4 = new Map();
map1.forEach((val, key) => {map4.set(key, val)});
map2.forEach((val, key) => {map4.set(key, val)});
```

This is the `merge foreach` approach. It iterates over both Maps using `forEach()` and sets each key-value pair in a new Map.

```javascript
var map5 = new Map();
map1.forEach((val, key) => {map5.set(key, val)});
var map6 = new Map();
map2.forEach((val, key) => {map6.set(key, val)});
var map7 = new Map([...map5, ...map6]);
```

This is an alternative implementation of the `merge 2 foreach` approach.

**Pros and Cons**

* `merge 2 foreach`: This approach uses the spread operator, which can be more concise and readable. However, it may not be as efficient as other approaches since it creates a new array of key-value pairs.
* `merge foreach`: This approach is more explicit about iterating over each Map. It may be less concise but can provide better performance since it avoids creating a new array.
* Alternative implementation: This approach uses the spread operator again, which can be beneficial if you need to merge multiple Maps.

**Library and Purpose**

None of the provided test cases use any external libraries beyond the built-in JavaScript `Map` object.

**Special JS Features or Syntax**

The benchmark does not mention any special JavaScript features or syntax. However, it's worth noting that using spread operators (`...`) is a relatively modern feature introduced in ECMAScript 2018 (ES9).

**Other Alternatives**

* Using the `Set` object instead of `Map`: You can also merge two Sets using the spread operator.
```javascript
var set1 = new Set([1, 2, 3]);
var set2 = new Set([4, 5, 6]);
var mergedSet = new Set([...set1, ...set2]);
```
* Using the `reduce()` method: You can merge two Maps using the `reduce()` method.
```javascript
var map1 = new Map([[1, 'Val 1'], [2, 'Val 2']]);
var map2 = new Map([[3, 'Val 3'], [4, 'Val 4']]);
var mergedMap = new Map();
map1.forEach((val, key) => {mergedMap.set(key, val)});
map2.forEach((val, key) => {mergedMap.set(key, val)});
```
These alternatives may offer different trade-offs in terms of performance and conciseness.

Related benchmarks:

merge maps (version: 0)

Comparing performance of: Merge spread vs merge foreach vs merge 2 foreach

Created: 4 years ago by: Registered User

Jump to the latest result

Merge spread

merge foreach

merge 2 foreach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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