Benchmark: Array.from vs Spread. Map 1000000

Script Preparation code:

var fooMap = new Map();
for(var i=0;i<10000000;i++) {
  fooMap.set(i, { id: i });
}

Tests:

Array.from
var other = Array.from(fooMap, ([name, value]) => value);
Spread
var other = [...fooMap].map(([name, value]) => value);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from
Spread

Fastest: N/A

Slowest: N/A

Latest run results:

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

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

**Benchmark Overview**

The benchmark is comparing two approaches to iterate over a Map object in JavaScript:

1. `Array.from`
2. Spread operator (`...`)

The goal is to find out which approach is faster, more efficient, or has better performance for this specific use case.

**What's Being Tested?**

In the `Script Preparation Code`, we have a Map object `fooMap` created with 10 million entries. The purpose of this code is to populate the map with data that will be used in the subsequent test cases.

The two test cases compare how long it takes for each approach to:

* Iterate over the Map entries
* Extract values from the Map using the spread operator (`[...]`) or `Array.from` function

**Options Compared**

Let's break down the options being compared:

### 1. `Array.from`

This method creates a new Array instance and populates it with the elements of the original map.

```javascript
var other = Array.from(fooMap, ([name, value]) => value);
```

Pros:

* Can be used with any iterable (not just Maps)
* May be more flexible in certain situations

Cons:

* Creates an additional Array object, which can consume memory and cause performance issues for very large datasets.

### 2. Spread Operator (`...`)

This method uses the spread operator to create a new array from the elements of the original map.

```javascript
var other = [...fooMap].map(([name, value]) => value);
```

Pros:

* More concise and expressive than `Array.from`
* Can be used directly on arrays and iterables without creating an intermediate object

Cons:

* May not be as flexible as `Array.from` in certain situations
* Can create a new array with duplicate values if the iterable has duplicate entries.

**Library Used**

In both test cases, we're using the `Map` data structure from JavaScript's built-in `Object` namespace. The purpose of this library is to provide a simple way to store key-value pairs and iterate over them efficiently.

**Special JS Feature or Syntax**

There are no special features or syntax used in this benchmark that require a specific understanding of advanced JavaScript concepts. However, the use of `Map` and the spread operator may be unfamiliar to developers who haven't worked with these data structures before.

**Other Alternatives**

If you wanted to write a similar benchmark, you could consider adding additional test cases for other approaches, such as:

* Using a traditional `for...in` loop
* Using the `forEach()` method
* Using a library like Lodash's `mapKeys()` function

However, keep in mind that each alternative approach may have its own pros and cons, and may not necessarily outperform the existing options.

**Benchmark Preparation Code**

The provided script preparation code is used to create a Map object with 10 million entries. This code is executed before running the benchmark test cases.
```javascript
var fooMap = new Map();
for (var i = 0; i < 10000000; i++) {
  fooMap.set(i, { id: i });
}
```
This code creates a Map object and populates it with data that will be used in the subsequent test cases.

Related benchmarks:

Array.from vs Spread. Map 1000000 (version: 0)

Comparing performance of: Array.from vs Spread

Created: 3 years ago by: Guest

Jump to the latest result

Array.from

Spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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