Benchmark: Array loop vs foreach vs map 36000

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 36000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }

Tests:

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

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Autogenerated LLM Summary (model llama3.1:latest, generated one year ago):

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Let's dive into the details of this benchmark.

**What is being tested?**

This benchmark compares three different ways to iterate over an array in JavaScript:

1. **forEach**: Using the `forEach()` method, which executes a provided function once for each element in the array.
2. **for loop**: Using a traditional for loop with a counter variable `i` that iterates over the array indices.
3. **map**: Using the `map()` method, which creates a new array with the results of applying a provided function to each element in the original array.

**What options are compared?**

The benchmark compares the execution speed (measured by executions per second) of these three approaches on an array of 36,000 elements. The test cases use a simple function `someFn()` that multiplies its input by 3 and then by 8.

**Pros/Cons of each approach:**

1. **forEach**: Pros:
	* Easy to read and write.
	* No need to worry about index boundaries (as the loop is automatically managed).
	* Can be used with array-like objects.
	* Supports a callback function that can return values or side effects.

Cons:
		* May have performance overhead due to the added overhead of creating a scope for each iteration.
2. **for loop**: Pros:
	* Traditionally fast and efficient, as it's just a simple iteration over indices.
	* Easy to reason about and optimize manually (e.g., by caching or skipping iterations).

Cons:
		* May lead to index out-of-bounds errors if not properly managed.
		* Requires manual handling of loop logic.
3. **map**: Pros:
	* Creates a new array with the results, making it easy to chain operations.
	* Supports a concise and readable syntax.

Cons:
		* May have performance overhead due to the creation of a new array.
		* Requires understanding of functional programming concepts (e.g., immutability).

**Library and purpose:**

None. This benchmark is based on standard JavaScript features, with no additional libraries used.

**Special JS feature or syntax:**

The `map()` method uses an arrow function (`item => someFn(item)`) to transform each element in the array. This is a modern JavaScript feature (introduced in ECMAScript 2015) that allows for concise and expressive code.

**Alternatives:**

For iterating over arrays, you can use other methods like:

1. **reduce()**: Accumulates values from left to right.
2. **filter()**: Creates a new array with elements that pass a test condition.
3. **every()** or **some()**: Check if all or some elements in the array meet a condition.
4. **while loop**: A traditional looping construct that's less common for array iteration.

Each of these methods has its strengths and weaknesses, depending on your specific use case. The benchmark shows that `forEach` and `map` are relatively fast, while the traditional `for` loop is still competitive in terms of performance.

Related benchmarks:

Array loop vs foreach vs map 36000 (version: 0)

36000

Comparing performance of: foreach vs for vs map

Created: 4 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 llama3.1:latest, generated one year ago):