Benchmark: Array immutability vs mutability

Tests:

push
const data = []; for (let i = 0; i < 10000; ++i) data.push(i);
spread
let data = []; for (let i = 0; i < 10000; ++i) [...data,i];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
push
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):

LLMs can make mistakes. Check important info.

Let's dive into explaining the provided benchmark.

**What is tested:**
The benchmark tests two approaches to creating an array in JavaScript:

1. `push`: This approach creates an empty array and then uses the `push` method to add elements to it. The array grows in size by 10,000 elements.
2. `spread`: This approach creates an empty array and then uses the spread operator (`[...]`) to create a new array with the original array as its first element, followed by the numbers from 0 to 9,999.

**Options compared:**
The benchmark compares the performance of these two approaches:

* Push vs Spread

**Pros and Cons:**

* `push`:
	+ Pros: Simple and intuitive.
	+ Cons: Can be slower due to the overhead of resizing the array.
* `spread`:
	+ Pros: Faster, as it creates a new array with the desired size.
	+ Cons: Requires understanding of the spread operator and may be less intuitive.

**Library usage:**
None of the test cases use any libraries. The benchmark only relies on built-in JavaScript features.

**Special JS feature or syntax:**
The `spread` operator (`[...]`) is used in the second test case. This operator creates a new array by copying elements from an existing array and adds new elements to it. It's a convenient way to create arrays with a desired size, but its performance can vary depending on the browser and JavaScript engine.

**Other alternatives:**
If you wanted to test different approaches to creating an array in JavaScript, you could consider adding additional test cases for:

* `Array.from()`: Creates a new array from an iterable object.
* `Array.prototype.slice()`: Creates a shallow copy of a portion of an array.
* `Array.prototype.concat()`: Concatenates two or more arrays.

Here's an example of how the benchmark definition JSON could be updated to include additional test cases:

```json
{
    "Name": "Array creation",
    "Description": null,
    "Script Preparation Code": null,
    "Html Preparation Code": null
}

Individual test cases: [
    {
        "Benchmark Definition": "const data = [];\r\nfor (let i = 0; i < 10000; ++i) data.push(i);",
        "Test Name": "push"
    },
    {
        "Benchmark Definition": "let data = [];\r\nArray.from(data, () => null);\r\nfor (let i = 0; i < 10000; ++i) data.push(i);",
        "Test Name": "from"
    },
    {
        "Benchmark Definition": "let data = [];\r\ndata = [...data];\r\nfor (let i = 0; i < 10000; ++i) data.push(i);",
        "Test Name": "slice"
    },
    {
        "Benchmark Definition": "let data = [];\r\ndata = [...data, ...Array.from({ length: 10000 }, () => null)];",
        "Test Name": "concat"
    }
]
```

Keep in mind that adding more test cases may increase the complexity of the benchmark and require more time to run.

Related benchmarks:

Array immutability vs mutability (version: 0)

Comparing performance of: push vs spread

Created: 6 years ago by: Guest

Jump to the latest result

push

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):