Benchmark: little test - MeasureThat.net

Script Preparation code:

data = [{"a": 1, "b": 2}, {"c": 1, "d": 2}, {"e": 1, "f": 2}];

function newArr(arr) {
	const len = arr.length - 1;
  	const ret = [];
  	for (let i = 0; i < len; i++) ret.push(i);
  	return ret;
}

Tests:

A
let val = data.slice(0, -1).map((value, index) => index);
B
let val = newArr(data);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
A
B

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 the benchmark definition and test cases.

**Benchmark Definition:**

The provided JSON represents a JavaScript microbenchmark, which is a small piece of code designed to measure the performance of specific parts of the JavaScript engine.

In this case, there are two benchmark definitions:

1. `"let val = data.slice(0, -1).map((value, index) => index);"`
2. `"let val = newArr(data);"`

These benchmarks aim to test the performance of different methods in JavaScript arrays: `slice` and `map` with a callback function.

**New Array Function (newArr):**

The `newArr` function is not a built-in JavaScript method. Instead, it's a custom implementation provided in the benchmark preparation code:

```javascript
function newArr(arr) {
    const len = arr.length - 1;
    const ret = [];
    for (let i = 0; i < len; i++) ret.push(i);
    return ret;
}
```

This function is designed to produce a new array with the same length as the input array, but it does so by creating an array with indices from `0` to `length - 1`. The purpose of this benchmark is likely to test how efficient JavaScript engines can iterate over arrays.

**Pros and Cons:**

* Using `slice(0, -1)` creates a new array with all elements except the last one. This approach may be slower because it involves creating a new array.
* Using `newArr` function, as implemented above, produces an array with indices from 0 to length - 2 (because of `arr.length - 1`). This approach might be faster for some engines due to reduced array creation.

It's worth noting that the performance difference between these two approaches may vary depending on the JavaScript engine and browser being used.

**Browser Comparison:**

The latest benchmark result shows two test cases:

* Test A (using `slice(0, -1)`): 4577593.5 executions per second
* Test B (using `newArr` function): 3670425.25 executions per second

This suggests that the `slice(0, -1)` approach is slightly faster than using the custom `newArr` function.

**Other Alternatives:**

If you wanted to create similar benchmarks, you could consider exploring other methods for testing array performance, such as:

* Using `map()` with a simple callback function
* Creating an array with indices from 0 to length - 1 using `Array.from()`
* Comparing the performance of different array iteration approaches, such as `forEach()`, `for...of` loops, and `reduce()`

Keep in mind that these alternatives may not directly compare to the original benchmarks but can provide a fresh perspective on measuring JavaScript array performance.

Related benchmarks:

little test (version: 0)

Comparing performance of: A vs B

Created: 6 years ago by: Guest

Jump to the latest result

A

B

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):