Benchmark: Loop comparison - MeasureThat.net

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
  arr[i] = Math.random();
}

Tests:

For [cached]
for (var i = 0, len = arr.length; i < len; i++) { arr[i] *= 2; }
For [not cached]
for (var i = 0; i < arr.length; i++) { arr[i] *= 2; }
While
var len = arr.length while (len--) { arr[i] *= 2; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
For [cached]
For [not cached]
While

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.

**Overview of the Benchmark**

The provided benchmark compares three approaches to iterating over an array in JavaScript: using `for` loops with caching, without caching (`for` loop), and using a `while` loop.

**Tested Options**

1. **For [cached]**: This approach uses a cached value to improve performance. The `len` variable is declared outside the loop, reducing the overhead of repeated array length checks.
2. **For [not cached]**: This is a basic `for` loop that iterates over the array without caching the length.
3. **While**: This approach uses a `while` loop to iterate over the array, which can be more efficient than traditional `for` loops in some cases.

**Pros and Cons**

* **For [cached]**:
	+ Pros: Reduces array length check overhead, potentially faster execution.
	+ Cons: May not work correctly for arrays with negative indices or non-numeric lengths, requires extra memory to store the cached value.
* **For [not cached]**:
	+ Pros: Simple and well-supported, works correctly with all types of arrays.
	+ Cons: Slower due to repeated array length checks.
* **While**:
	+ Pros: Can be more efficient than traditional `for` loops for large arrays or when the loop condition is known at compile-time.
	+ Cons: More complex and harder to read, may not work correctly with all types of arrays.

**Library Used**

None of the provided benchmark scripts use any external libraries. However, it's worth noting that the `Array.prototype.length` property is used in all three approaches, which is a standard JavaScript API.

**Special JS Feature or Syntax**

None of the benchmark scripts explicitly use any special JavaScript features or syntax. The code is written in vanilla JavaScript and uses only basic language constructs.

**Other Alternatives**

If you're interested in exploring alternative approaches to iterating over arrays, here are some options:

* **Array.prototype.forEach()**: A more modern approach that's supported by most browsers, which eliminates the need for explicit loops.
* **Array.prototype.map()**, **Array.prototype.filter()**, and **Array.prototype.reduce()**: Methods that can be used to transform or reduce array elements without explicit looping.

These alternatives are often preferred in modern JavaScript development due to their readability, maintainability, and performance benefits. However, they may not always be suitable for specific use cases or older browsers that don't support them.

Related benchmarks:

Loop comparison (version: 0)

Comparing performance of: For [cached] vs For [not cached] vs While

Created: 6 years ago by: Registered User

Jump to the latest result

For [cached]

For [not cached]

While

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):