Benchmark: destru vs for - MeasureThat.net

Script Preparation code:

window.arr = [];
for (let i = 0; i < 100000; i++) {
  window.arr.push(i);
}

Tests:

for each
const len = window.arr.length; const forArray = []; for (let i = 0; i < len; i++) { forArray.push(i); } console.log("forArray.length", forArray.length);
destruct
const desArray = []; desArray.push(...window.arr); console.log("desArray.length", desArray.length);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for each
destruct

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.

I'll break down the benchmark test cases and explain what's being tested.

**Benchmark Test Cases**

The provided JSON contains two individual test cases: "for each" and "destruct". Each test case has its own JavaScript code that is executed in a web browser.

**Test Case 1: "for each"`

In this test case, we have the following code:
```javascript
const len = window.arr.length;
const forArray = [];
for (let i = 0; i < len; i++) {
  forArray.push(i);
}
console.log("forArray.length", forArray.length);
```
This code creates an array `window.arr` with 100,000 elements and then uses a nested `for` loop to push each element into another array `forArray`. The length of the resulting array is then logged to the console.

**Test Case 2: "destruct"`

In this test case, we have the following code:
```javascript
const desArray = [];
desArray.push(...window.arr);
console.log("desArray.length", desArray.length);
```
This code creates an empty array `desArray` and then uses the spread operator (`...`) to push all elements from `window.arr` into `desArray`. The length of the resulting array is then logged to the console.

**Options Compared**

The two test cases compare two different approaches to iterate over the elements of `window.arr`.

1. **Nested `for` loop**: The first test case uses a nested `for` loop, where an outer loop iterates over the indices of `window.arr`, and an inner loop pushes each element into `forArray`.
2. **Spread operator (`...`)**: The second test case uses the spread operator to push all elements from `window.arr` into `desArray`.

**Pros and Cons**

* **Nested `for` loop**:
	+ Pros: Can be more readable for complex iteration patterns.
	+ Cons: Can be slower due to the overhead of function calls and loop control.
* **Spread operator (`...`)**:
	+ Pros: Can be faster due to the use of a built-in operation.
	+ Cons: May not work as expected if `window.arr` contains non-array elements.

**Library and Purpose**

There is no library explicitly mentioned in the provided code. However, it's worth noting that some modern JavaScript engines (e.g., V8) have optimized implementations for the spread operator (`...`) that can provide performance benefits.

**Special JS Feature or Syntax**

The spread operator (`...`), used in the second test case, is a special feature introduced in ECMAScript 2015. It allows elements to be pushed into an array from another iterable (e.g., `window.arr`).

**Other Alternatives**

There are other ways to iterate over the elements of `window.arr`, such as using `forEach()` or a `for...of` loop:
```javascript
// Using forEach()
const forArray = [];
window.arr.forEach((element) => {
  forArray.push(element);
});
```

```javascript
// Using for...of loop
const desArray = [];
for (const element of window.arr) {
  desArray.push(element);
}
```
These alternatives may have different performance characteristics and readability, depending on the specific use case.

Related benchmarks:

destru vs for (version: 0)

destru vs for

Comparing performance of: for each vs destruct

Created: 5 years ago by: Guest

Jump to the latest result

for each

destruct

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):