Benchmark: Array loop vs foreach vs map gilad2

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(item => someFn(item));
for
for (let i = 0, n=arr.length; i < n; 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

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**What is being tested?**

The provided benchmark tests three different approaches to iterate over an array in JavaScript: `forEach`, `for` loop, and `map`. The script preparation code creates an empty array of length 1000, populates it with numbers from 0 to 999, and defines a simple function `someFn(i)` that takes an input `i` and returns the result of `i * 3 * 8`.

**Options compared**

The three options are compared in terms of execution speed. The benchmark measures the number of executions per second for each option.

**Pros and cons of each approach:**

1. **`forEach` loop:**
	* Pros:
		+ Concise and expressive syntax.
		+ Easy to read and write.
	* Cons:
		+ Can be slower than `for` loops because of the overhead of function calls.
2. **`for` loop:**
	* Pros:
		+ Often faster than `forEach` due to fewer function call overheads.
		+ Allows for manual control over iteration and optimization.
	* Cons:
		+ More verbose syntax can make it harder to read and write.
3. **`map` method:**
	* Pros:
		+ Concise and expressive syntax.
		+ Avoids the need for explicit loop logic.
	* Cons:
		+ Can be slower than `for` loops due to function call overheads.

**Library usage**

There is no library explicitly mentioned in the benchmark definition. However, it's worth noting that some JavaScript engines (like V8) have built-in optimizations and features that might affect the performance of these benchmarks.

**Special JS feature or syntax**

None are explicitly mentioned in this benchmark.

**Other considerations**

The benchmark assumes a modern JavaScript engine that supports `forEach` and `map` methods. The use of an empty array to populate with numbers from 0 to 999 is likely done for simplicity and to isolate the variable being tested (the iteration method).

**Alternative approaches**

Some alternative approaches to iterating over arrays in JavaScript include:

1. **Array.prototype.reduce()**: Similar to `map`, but accumulates a value instead of returning an array.
2. **Array.prototype.filter()`: Returns a new array with elements that pass a test, similar to `map` but with filtering capabilities.
3. **Manual iteration using `for...in` or `for...of` loops**: These can be more verbose than the other options but offer fine-grained control over iteration.

These alternatives might not be as concise or expressive as `forEach`, `for`, and `map`, but they can provide more flexibility and customization options.

Related benchmarks:

Array loop vs foreach vs map gilad2 (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):