Benchmark: Array loop vs foreach vs map -2

Script Preparation code:

var arr = [];
for (let i = 0; i < 1000; i++) {
  arr[i] = i;
}
  
function someFn(i) {
  return i * 3 * 8;
}

Tests:

foreach
arr.forEach(someFn)
for
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
map
arr.map(someFn)

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

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark measures the performance of three different loops in JavaScript: `foreach`, `for`, and `map`. The test case uses a fixed-size array `arr` with 1000 elements, initialized with values from 0 to 999. Each loop iterates over this array, applying a simple function `someFn(i)` that multiplies the input by 3 and 8.

**Options Compared**

The three loops being compared are:

1. **Array.prototype.forEach()**: This method calls the provided callback function for each element in the array, without requiring explicit indexing.
2. **Manual Loop with Indexing**: This approach uses a traditional `for` loop to iterate over the array elements by their index.
3. **Array.prototype.map()**: This method creates a new array with the results of applying the provided callback function to each element.

**Pros and Cons of Each Approach**

1. **Array.prototype.forEach()**
	* Pros:
		+ Convenient syntax for iterating over arrays without explicit indexing.
		+ Good performance, as it avoids unnecessary bounds checking.
	* Cons:
		+ May have slower performance compared to manual looping or `map()` due to overhead from callback function execution.
2. **Manual Loop with Indexing**
	* Pros:
		+ Typically faster than `forEach()` and `map()`, as there's no overhead from callback functions.
	* Cons:
		+ Requires explicit indexing, which can lead to errors if not handled carefully.
3. **Array.prototype.map()**
	* Pros:
		+ Creates a new array with transformed elements, allowing for more flexibility.
		+ Can be faster than `forEach()` when dealing with large arrays and caching of intermediate results.
	* Cons:
		+ May have slower performance compared to manual looping due to creation of a new array.

**Special Considerations**

The benchmark doesn't use any special JavaScript features or syntax beyond the standard language. However, it's worth noting that modern browsers may optimize certain methods or functions, which could affect the results.

**Alternative Approaches**

Other alternatives for iterating over arrays in JavaScript include:

1. **Array.prototype.forEach.call()**: Similar to `forEach()` but allows for a custom context object.
2. **Set-based iteration**: For arrays with unique elements, using `Set` and its methods can be more efficient than traditional looping.

For more complex or large-scale performance benchmarks, consider exploring additional JavaScript performance testing tools and frameworks, such as WebPageTest or JSHint.

Related benchmarks:

Array loop vs foreach vs map -2 (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):