Benchmark: array.from vs array slice

Script Preparation code:

var testIterable = function* generateIterable() {
  for (let i = 0; i < 100; i++) {
    yield i;
  }
}

Tests:

Array.from
const arr = Array.from(testIterable());
Array slice
const arrs = Array.prototype.slice.call(testIterable());

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from
Array slice

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Windows

View result in a separate tab

Test name	Executions per second
Array.from	573457.3 Ops/sec
Array slice	10643649.0 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.

**What is being tested?**

The benchmark measures the performance of two approaches to create an array from an iterable:

1. `Array.from()`
2. `Array.prototype.slice.call()` (often referred to as "array slice")

In this specific case, the test case uses a generator function `testIterable` to generate an array of numbers from 0 to 99.

**Options compared**

The benchmark compares two options for creating an array from an iterable:

1. **`Array.from()`**: This method creates a new array from an iterable (such as an array, object, or any other type of iterable) by mapping each element to a new array value.
2. **`Array.prototype.slice.call()`** (or simply "array slice"): This approach uses the `slice()` method on an array and then passes the result to `call()` with an array of arguments.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **`Array.from()`**:
	* Pros:
		+ More concise and expressive syntax.
		+ Often faster, as it can take advantage of optimized internal algorithms.
	* Cons:
		+ May have performance issues if the iterable is very large or complex.
2. **`Array.prototype.slice.call()` (array slice)**:
	* Pros:
		+ Can be more efficient for very large iterables, as it allows the browser to optimize the `slice()` method.
	* Cons:
		+ Less concise and expressive syntax compared to `Array.from()`.
		+ May have additional overhead due to the use of `call()`.

**Library usage**

In this benchmark, no external libraries are used. However, if you were to extend this benchmark to compare other approaches, you might consider using libraries like Lodash or Ramda, which provide a range of utility functions for working with arrays and iterables.

**Special JavaScript feature/syntax**

There is no special JavaScript feature or syntax mentioned in this benchmark. The test cases rely solely on standard JavaScript features and syntax.

**Other alternatives**

If you wanted to compare other approaches to creating an array from an iterable, some possible alternatives could include:

* Using `Array.prototype.concat()` to concatenate multiple iterables.
* Using a for loop with indexing to create the array.
* Using a custom implementation of an iterator or generator function.

Keep in mind that each of these alternative approaches would have its own pros and cons, which would need to be carefully considered when designing a benchmark.

Related benchmarks:

array.from vs array slice (version: 0)

Comparing performance of: Array.from vs Array slice

Created: 5 years ago by: Registered User

Jump to the latest result

Array.from

Array slice

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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