Benchmark: Array from() vs Map.keys()

Tests:

Array.from
var fooMap = new Map(); for(var i=0;i<10000;i++) { fooMap.set(i, i); } var other = [...fooMap];
Map.keys
var fooMap = new Map(); for(var i=0;i<10000;i++) { fooMap.set(i, i); } var other = fooMap.keys();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from
Map.keys

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:128.0) Gecko/20100101 Firefox/128.0

Browser/OS: Firefox 128 on Windows

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Test name	Executions per second
Array.from	919.5 Ops/sec
Map.keys	1599.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Definition**

The benchmark is defined by two test cases: `Array.from()` and `Map.keys()`. These are both methods used to convert an iterable (like an array or map) into a new array or object. The main difference between them lies in how they approach this conversion:

*   `Array.from()`: This method creates a new array from an iterable or an array-like object. It takes an iterable as an argument and returns a new array with the elements of that iterable.
*   `Map.keys()`: This method returns a iterator over the keys of a map (an object that stores key-value pairs). This iterator can be used to create a new iterable, like an array.

**Options Compared**

The benchmark is comparing two approaches:

1.  Using `Array.from()` to convert a map into an array.
2.  Using `Map.keys()` directly to get an iterator over the keys of the map and then creating an array from that iterator.

**Pros and Cons**

Here are some pros and cons for each approach:

*   **Using `Array.from()`**: 
    *   Pros:
        *   More concise code
        *   May be faster in some cases (because it avoids the overhead of using `Map.keys()`)
    *   Cons:
        *   Creates a new array, which may consume more memory for large inputs.
        *   Does not take advantage of any special properties of the input map that could make the operation more efficient.

*   **Using `Map.keys()`**:
    *   Pros:
        *   Does not create a new array, so it can be more memory-efficient than using `Array.from()`.
        *   Can potentially be faster because it avoids creating an intermediate array.
    *   Cons:
        *   Requires the input to be a map (which may not always be the case).
        *   May be slower because of the overhead of working with iterators.

**Library Used**

In this benchmark, none are explicitly stated as used by test users. However, in JavaScript `Map` and its methods like `keys()` and `values()`, are built-in.

**Special JS Feature or Syntax**

The feature used here is that of using `Map` object, which is a fundamental part of the JavaScript standard library for working with collections of key-value pairs. It was introduced in ECMAScript 2015 (ES6).

**Other Alternatives**

There are several other ways to convert an iterable into a new array or object:

*   **Using `Array.prototype.slice()` or `Array.from().slice()`**: These methods create a shallow copy of the input array, but they can be slower than using `Array.from()`.
*   **Using `String.prototype.split()`**: This method splits a string into an array of substrings.
*   **Using `Array.prototype.map()` and `Array.prototype.reduce()`**: These methods can be used to transform an iterable into an array. However, they are more computationally expensive than using `Array.from()`.

Related benchmarks:

Array from() vs Map.keys() (version: 0)

Comparing performance of: Array.from vs Map.keys

Created: 4 years ago by: Guest

Jump to the latest result

Array.from

Map.keys

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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