Benchmark: Array.prototype.slice vs spread operator - objects

Script Preparation code:

    function fromNumberToObject(id = 0) {
      return {
        id,
        value: id + id,
        name: 'example',
      };
    }
    var list = [...Array(100000).keys()].map(fromNumberToObject);

Tests:

Array.prototype.slice
list.slice();
spread operator
[...list];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.prototype.slice
spread operator

Fastest: N/A

Slowest: N/A

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

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Let's break down the benchmark and explain what's being tested, compared, and what the pros and cons of each approach are.

**Benchmark Definition:**

The website MeasureThat.net is comparing two approaches to create a copy of an array in JavaScript:

1. **Array.prototype.slice()**: This method creates a shallow copy of a portion of an array.
2. **Spread Operator (`[...]`)**: This operator creates a new array by spreading the elements of an existing array.

**Script Preparation Code:**

The script preparation code creates an array of 100,000 objects with `id`, `value`, and `name` properties using a helper function `fromNumberToObject()`. The resulting array is stored in the variable `list`.

**Html Preparation Code:**

There is no HTML preparation code provided.

**Individual Test Cases:**

The benchmark has two test cases:

1. **Array.prototype.slice()**: This test case runs the `slice()` method on the `list` array.
2. **Spread Operator (`[...]`)**: This test case uses the spread operator to create a new array from the `list` array.

**Library and Purpose:**

There is no explicitly mentioned library, but the `Array.prototype.slice()` method is a built-in method of the JavaScript Array prototype.

The spread operator (`[...]`) was introduced in ECMAScript 2015 (ES6) as a new way to create arrays. It's intended to provide a more concise and expressive way to create copies of arrays.

**Special JS Feature or Syntax:**

There is no special JavaScript feature or syntax mentioned, but it's worth noting that the spread operator was introduced in ES6, which may not be supported by older browsers or versions of JavaScript.

**Pros and Cons of each approach:**

1. **Array.prototype.slice()**:
	* Pros:
		+ Widely supported across different browsers and JavaScript versions.
		+ Can be used to create shallow copies of arrays with a specific subset of elements.
	* Cons:
		+ May not be as efficient as the spread operator for large arrays, as it involves creating a new array object and copying elements from the original array.
2. **Spread Operator (`[...]`)**:
	* Pros:
		+ More concise and expressive than `slice()`.
		+ Can create shallow copies of entire arrays or subsets of arrays.
	* Cons:
		+ May not be supported by older browsers or JavaScript versions that don't support ES6 features.
		+ Can be slower than `slice()` for very large arrays due to the overhead of creating a new array object.

**Other Alternatives:**

If you need to create a copy of an array, other alternatives include:

1. **Array.from()**: This method creates a new array from an iterable or an array-like object.
2. **Array.prototype.concat()**: This method returns a new array that contains the elements of multiple arrays.
3. **Object.assign()**: This method copies elements from one or more source objects to a target object.

Each of these alternatives has its own trade-offs and use cases, and it's essential to choose the best approach based on your specific requirements and performance constraints.

Related benchmarks:

Array.prototype.slice vs spread operator - objects (version: 0)

Compare the new ES6 spread operator with the traditional slice() method

Comparing performance of: Array.prototype.slice vs spread operator

Created: 5 years ago by: Guest

Jump to the latest result

Array.prototype.slice

spread operator

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):