Benchmark: Shift loop vs unrolled

Tests:

Shift loop
const arr = []; const ARRAY_SIZE = 5000; for (let i = 0; i < ARRAY_SIZE; i++) { arr.push(i); } while(arr.length) { let index = arr.shift(); index++; }
Unrolled Loop
let arr = []; const ARRAY_SIZE = 5000; for (let i = 0; i < ARRAY_SIZE; i++) { arr.push(i); } const arrSize = arr.length; for (let i = 0; i < arrSize; i++) { let index = arr[i]; index++; } arr = [];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Shift loop
Unrolled Loop

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 dive into the world of JavaScript microbenchmarks!

**Benchmark Overview**

The provided benchmark measures the performance difference between two approaches to incrementing an array element: a traditional `shift` loop and an unrolled loop.

**Shift Loop**

The Shift loop uses the built-in `shift()` method to remove and return the first element from the array, and then increments the returned value. The loop continues until the array is empty.

```javascript
for (let i = 0; i < ARRAY_SIZE; i++) {
  arr.push(i);
}
while(arr.length) {
  let index = arr.shift();
  index++;
}
```

**Unrolled Loop**

The Unrolled Loop uses a traditional for loop to iterate over the array elements, and then increments each element directly. The loop continues until all elements have been processed.

```javascript
for (let i = 0; i < ARRAY_SIZE; i++) {
  let arr[i]++;
}
arr = [];
```

**Comparison**

The benchmark compares the performance of these two approaches using a variety of options, including:

* **Execution Speed**: Measured in executions per second.
* **Device Platform**: Windows, Mac, or other platforms.
* **Browser Version**: The version of the browser used for the benchmark.

**Pros and Cons**

* **Shift Loop**
	+ Pros: Built-in `shift()` method provides a simple and efficient way to remove elements from an array.
	+ Cons: May be slower due to the overhead of the `shift()` method and the need to increment the returned value.
* **Unrolled Loop**
	+ Pros: Can be faster since it avoids the overhead of the `shift()` method and allows for direct access to array elements.
	+ Cons: Requires manual memory management (clearing the array) and can lead to errors if not implemented correctly.

**Library and Special JS Features**

No libraries are used in these benchmark cases. However, note that some JavaScript engines may optimize or modify the behavior of built-in methods like `shift()` or `push()`. In this case, the `shift()` method is likely to be implemented using a specialized algorithm optimized for performance.

**Other Alternatives**

If you're looking for alternative approaches to incrementing array elements, consider:

* Using `array.fill()` instead of `push()` and manual indexing.
* Utilizing libraries like `lodash` or `ramda` that provide optimized array methods.
* Implementing your own custom array incrementation function using bitwise operations.

Keep in mind that the choice of approach depends on the specific use case, performance requirements, and personal preference.

Related benchmarks:

Shift loop vs unrolled (version: 0)

Comparing performance of: Shift loop vs Unrolled Loop

Created: 9 years ago by: Guest

Jump to the latest result

Shift loop

Unrolled Loop

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):