Benchmark: foreach vs for loop - kostia

Script Preparation code:

function generateTestArray() {
    const arr = [Array(50000).keys()];
    return arr;
}

Tests:

for loop
const array = generateTestArray(); console.time("for"); for(let i=0; i<array.length; i++) {} console.time("for end");
foreach loop
const array = generateTestArray(); console.time("foreach"); array.forEach(value=>{}); console.time("foreach end");

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop
foreach loop

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model gemma2:9b, generated one year ago):

LLMs can make mistakes. Check important info.

This benchmark compares the performance of two ways to iterate over an array in JavaScript: using a `for` loop and using the `forEach` method.

**Options Compared:**

* **`for` loop:**  A traditional loop that explicitly iterates through indices of an array. This gives you direct control over the index and allows for more complex iteration logic if needed.
* **`forEach` method:** A higher-level function built into arrays in JavaScript. It takes a callback function as an argument, which is executed for each element in the array.

**Pros and Cons:**

* **`for` loop:**
    * **Pros:** Can be more performant in some cases due to potentially fewer function calls overhead compared to `forEach`.  Offers greater control over the iteration process.
    * **Cons:** More verbose syntax, requires explicit index management.
* **`forEach` method:**
    * **Pros:** Simpler and more concise syntax, avoids manual index management.
    * **Cons:** Can be slightly less performant than a `for` loop in some scenarios due to the function call overhead.

**Considerations:**

* **Readability:**  `forEach` is generally considered more readable for simple iterations. 
* **Performance:** The performance difference between `for` loops and `forEach` is often minimal, especially for small arrays. Microbenchmarks like this one are useful for identifying these subtle differences in specific scenarios.

**Alternatives:**

* **`for...of` loop:** A newer way to iterate over iterables (including arrays) in JavaScript. It's even more concise than `forEach` and often performs similarly or better.

Let me know if you have any other questions about this benchmark or JavaScript iteration techniques!

Related benchmarks:

foreach vs for loop - kostia (version: 0)

foreach vs for loop

Comparing performance of: for loop vs foreach loop

Created: 3 years ago by: Guest

Jump to the latest result

for loop

foreach loop

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model gemma2:9b, generated one year ago):