Benchmark: Array loop vs foreach vs map populate array with prealloc fixed

Script Preparation code:

var arr = [];
for (var i = 0; i < 1000; i++) {
    arr[i] = i;
}

var arr2 = [];

Tests:

foreach
arr2 = new Array(arr.length); var j = 0; arr.forEach(function (item){ arr2[j] = item; ++j; })
for
arr2 = new Array(arr.length); for (var i = 0, len = arr.length; i < len; i++) { arr2[i] = arr[i]; }
map
arr2 = arr.map(item => item)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

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 break down the benchmark and explain what is being tested.

The benchmark compares three approaches to populate an array with 1000 elements:

1. **Array loop**: This approach uses a traditional for loop to iterate over the range of numbers and assigns each value to the corresponding index in the `arr` array.
2. **Foreach**: This approach uses the `forEach` method to iterate over the values in the `arr` array and assigns each value to the corresponding index in the `arr2` array.
3. **Map**: This approach uses the `map` method to create a new array with the same length as the original array, and then iterates over the values using an arrow function.

Here are the pros and cons of each approach:

* **Array loop**:
	+ Pros: Can be more control over the iteration process, potentially faster for large arrays.
	+ Cons: Can be slower for small arrays due to overhead of the loop, and more prone to errors if not implemented correctly.
* **Foreach**:
	+ Pros: Concise and readable, easy to understand and maintain. Less error-prone than a traditional loop.
	+ Cons: May have performance issues for large arrays or complex iteration logic.
* **Map**:
	+ Pros: Concise and readable, can be faster for large arrays due to optimized map implementation in V8 engine (the JavaScript engine used by Google Chrome).
	+ Cons: May not be suitable for small arrays, as it creates a new array and iterates over the original array.

The `map` approach is likely the fastest of the three due to the optimized implementation in the V8 engine. However, the performance difference between these approaches may vary depending on the specific use case, array size, and JavaScript engine version.

Now, let's talk about libraries used in this benchmark:

* None are explicitly mentioned in the benchmark definition or test cases. However, it is likely that the `forEach` method is implemented using a library or framework-specific implementation, as it is not part of the standard ECMAScript specification.

As for special JavaScript features or syntax, none are explicitly mentioned in this benchmark. The only notable feature used is the `map` method, which is a built-in method in ECMAScript 5+.

To provide alternative implementations or variations, here are some examples:

* Using a different loop construct, such as `while` or `do-while`, instead of `for`.
* Adding error handling or edge cases to the array loop implementation.
* Optimizing the foreach implementation using techniques like caching or memoization.
* Implementing a custom map function using a different data structure or algorithm.

Keep in mind that these alternatives would likely change the performance characteristics and behavior of the benchmark, so it's essential to test and verify their results.

Related benchmarks:

Array loop vs foreach vs map populate array with prealloc fixed (version: 0)

Comparing performance of: foreach vs for vs map

Created: 5 years ago by: Guest

Jump to the latest result

foreach

for

map

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):