Benchmark: Array.from vs Array spread with mapping of values

Script Preparation code:

var arr = ['a', 'b', 'c'];

Tests:

Array.from
Array.from(arr, name => name + name)
Spread
[...arr].map(name => name +name)

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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I'd be happy to help explain the benchmark and its results.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark that compares two approaches for mapping values over an array: `Array.from` with a callback function, and the spread operator (`...`) with a mapped function.

**Approaches Compared**

Two approaches are compared:

1. **`Array.from(arr, name => name + name)`**: This approach uses the `Array.from()` method to create a new array from an existing iterable (in this case, the string array `arr`). The callback function takes each element of the array and returns its value with `name + name`. This creates a new array with the modified values.
2. **`[...arr].map(name => name + name)`**: This approach uses the spread operator (`...`) to create a new array from an existing iterable (in this case, the string array `arr`). The mapped function takes each element of the array and returns its value with `name + name`. This also creates a new array with the modified values.

**Pros and Cons**

* **`Array.from()`**: Pros:
	+ More explicit and readable syntax
	+ Can handle more complex transformations (e.g., multiple operations)
	+ Can be used with other array methods (e.g., `Array.prototype.map()`)
* Cons:
	+ Slightly slower than the spread operator for small arrays
	+ Requires creating an intermediate array
* **Spread Operator (`...`)**: Pros:
	+ Faster and more concise syntax
	+ Creates a new array without requiring intermediate operations
	+ Can be used with other array methods (e.g., `Array.prototype.map()`)
* Cons:
	+ Less explicit and readable syntax for some developers
	+ May not work as expected in older browsers or environments

**Library Usage**

There is no library usage mentioned in the benchmark. However, the `Array.from()` method is a part of the ECMAScript standard (ECMA-262), while the spread operator (`...`) was introduced in ECMAScript 2015 (ES6).

**Special JS Features/Syntax**

The benchmark uses the following special JavaScript features:

* **Arrow functions**: Used in the callback function for `Array.from()` and the mapped function for both approaches.
* **Spread operator (`...`)**: Used to create a new array from an existing iterable.

**Alternative Approaches**

Other alternatives could be used to achieve the same result, such as:

1. Using `forEach()` instead of `map()`: `arr.forEach(name => name += name);`
2. Using `reduce()` instead of `map()`: `arr.reduce((acc, name) => acc.concat(name + name), [])`
3. Using a traditional `for` loop: `var newArr = []; for (var i = 0; i < arr.length; i++) { newArr.push(arr[i] + arr[i]); }`

However, these alternatives may not be as efficient or concise as the original approaches.

Related benchmarks:

Array.from vs Array spread with mapping of values (version: 0)

Comparing performance of: Array.from vs Spread

Created: 5 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):