Benchmark: reassign vs splice

Tests:

reassign
function assign() { let i = []; for (let j = 0; j < 200; j++) { i.push('a'); } let p = i.length; i = []; return i; } assign();
splice
function splice() { let i = []; for (let j = 0; j < 200; j++) { i.push('a'); } let p = i.length; i.splice(0, p); return i; } splice();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reassign
splice

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):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, compared, and their pros/cons.

**What is being tested?**

The benchmark tests two different approaches to clear an array in JavaScript:

1. **Reassigning**: Assigning a new empty array to the variable `i`.
2. **Splicing**: Using the `splice()` method to remove all elements from the array `i`.

**Options compared:**

* Reassigning (`let i = [];`) vs
* Splicing (`i.splice(0, p);`)

**Pros and Cons of each approach:**

Reassigning:

Pros:

* Simple and straightforward way to clear an array.
* No side effects on the original array.

Cons:

* Creates a new empty array object, which can lead to increased memory allocation and garbage collection overhead.
* May not be as efficient for large arrays due to the additional memory allocation.

Splicing:

Pros:

* Does not create a new empty array object, reducing memory allocation and garbage collection overhead.
* Can be faster for large arrays since it modifies the original array in place.

Cons:

* Requires an extra step to clear the array after splicing (`i = i.length;`), which can lead to additional memory allocation.
* May have side effects on the original array if not used carefully.

**Library and syntax:**

Neither of these approaches relies on any specific JavaScript library. The syntax is built-in to JavaScript.

**Special JS feature or syntax:**

There are no special JavaScript features or syntax used in this benchmark. Both reassigning and splicing use only standard JavaScript operators and methods.

**Other alternatives:**

* Using `Array.prototype.fill()` instead of reassigning: `i.fill([], 0, i.length);`
* Using `Array.prototype.slice()` and concatenation instead of splicing: `return [...i].slice(0).concat([]);`

These alternatives may have different performance characteristics depending on the specific use case.

**Benchmark preparation code:**

The provided JSON does not contain any benchmark preparation code. In a typical benchmark, you would need to create an array with a large number of elements and then run the test cases multiple times to get accurate results.

**Raw UA String:**

The raw UA string represents the User Agent string reported by the browser being tested. This information can be useful for identifying the specific browser version and platform being used for testing.

Related benchmarks:

reassign vs splice (version: 0)

reassign vs splice

Comparing performance of: reassign vs splice

Created: 3 years ago by: Guest

Jump to the latest result

reassign

splice

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):