Benchmark: slice() vs spread operator

Script Preparation code:

var arr = ["bob", true, 64]

Tests:

slice
var slarr = arr.slice()
spread
var sprarr = [...arr]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
slice
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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Let's break down the provided benchmark and explain what's being tested.

**What is being tested?**

The benchmark compares the performance of two approaches to create a shallow copy of an array: using the `slice()` method versus the spread operator (`...`).

**Options compared**

Two options are being compared:

1. **`slice()` method**: The `slice()` method returns a new array that includes only the elements from the original array, starting at the specified index (in this case, 0).
2. **Spread operator (`...`)**: The spread operator is used to create a new array by spreading the elements of an existing array.

**Pros and cons of each approach**

1. **`slice()` method**
	* Pros:
		+ Generally faster than the spread operator (since it doesn't involve creating a new array).
		+ More explicit and predictable.
	* Cons:
		+ Less intuitive for developers who are not familiar with the `slice()` method.
2. **Spread operator (`...`)**
	* Pros:
		+ More concise and expressive.
		+ Easier to understand and use, especially for those familiar with array destructuring.
	* Cons:
		+ Generally slower than the `slice()` method due to the overhead of creating a new array.

**Other considerations**

Both approaches have their trade-offs. The spread operator creates a new array and copies all elements, whereas the `slice()` method only returns references to the original elements, which can be faster but also less predictable if modified later.

**Library used (none)**

There are no libraries mentioned in this benchmark definition.

**Special JS feature or syntax (none)**

No special JavaScript features or syntax are being tested in this benchmark.

Now, let's take a look at the test cases:

The test cases define two individual benchmarks:

1. **`slice()`**: Creates an array using the `slice()` method.
2. **`spread()`**: Creates an array using the spread operator (`...`).

Each test case executes its respective benchmark definition and reports the results, including the number of executions per second.

**Other alternatives**

If you're looking for alternative ways to create shallow copies of arrays in JavaScript, some other approaches include:

1. `Array.prototype.slice.call()`: A more explicit way to create a new array using the `slice()` method.
2. `Array.prototype.slice.apply()`: Similar to `slice.call()`, but uses the `apply()` method instead.
3. Using a library like Lodash or Ramda, which provide optimized implementations for creating arrays.

However, the `slice()` method and spread operator are generally considered the most common and efficient ways to create shallow copies of arrays in modern JavaScript.

Related benchmarks:

slice() vs spread operator (version: 0)

Comparing performance of: slice vs spread

Created: 5 years ago by: Guest

Jump to the latest result

slice

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):