Benchmark: Array.from vs spread 123

Script Preparation code:

function* iter() {
  for (let i = 0; i < 1000; i++) {
    yield i;
  }  
}

Tests:

Array.from
Array.from[iter()]
Spread
[...iter()]

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:

No previous run results

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

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Let's dive into explaining the benchmark.

The provided JSON represents a JavaScript microbenchmark that compares two approaches: `Array.from()` and the spread operator (`...`).

**What is being tested?**

In this benchmark, we're comparing the performance of creating an array from an iterable using two different methods:

1.  `Array.from()`: This method creates a new array from an existing iterable (like an array, set, map, or even a generator function like `iter()`).
2.  Spread operator (`...`): This syntax is used to expand an array into individual elements.

**Options being compared**

The two options being compared are:

1.  `Array.from()`: A built-in JavaScript method that creates a new array from an iterable.
2.  Spread operator (`...`): A shorthand syntax for creating a new array from individual elements.

**Pros and Cons of each approach:**

1.  `Array.from()`:

*   **Pros**: More explicit, easier to understand, and less prone to errors (since it's a well-defined method).
    *   **Cons**: May incur overhead due to the method call and object creation.
2.  Spread operator (`...`):

*   **Pros**: Shorter syntax, more concise, and can be faster since it avoids creating an intermediate object.
    *   **Cons**: Less explicit, which might lead to errors if not used correctly.

**Other considerations:**

*   The `iter()` function is a generator function that yields values one by one. It's likely used here as a simple example of an iterable.
*   JavaScript engines like V8 in Chrome (as seen in the benchmark result) often use various optimizations and heuristics to determine which approach is faster for specific workloads.

**Library usage:**

There is no library explicitly mentioned in this benchmark. However, it's worth noting that some libraries might provide their own implementations of these functions or offer additional features related to array creation.

**Special JS feature or syntax:**

The spread operator (`...`) is a shorthand syntax introduced in ECMAScript 2015 (ES6). It allows expanding an array into individual elements. This benchmark does not specifically test any other special JavaScript features or syntaxes, but it's essential to note that newer benchmarks might explore additional aspects.

**Alternative approaches:**

For this specific use case, the two primary alternatives are:

1.  Using `Array.from()` with a provided iterable (e.g., an array, set, or even a generator function).
2.  Manually creating an array using the `push()` method or other array mutation methods.

Other options might include:

*   Other spread-related operators like spread assignment (`...=`) or rest parameters (`...` in function calls).
*   Using libraries that provide optimized array creation functions (though this benchmark does not use any such libraries).

Keep in mind that microbenchmarks often focus on a specific, well-defined problem to ensure accurate results and avoid unnecessary complexity.

Related benchmarks:

Array.from vs spread 123 (version: 0)

Comparing performance of: Array.from vs Spread

Created: 4 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):