Benchmark: index loop vs for-of loop vs foreach vs map

Script Preparation code:

   var arr = [];
    for (var 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)
for-of
for (const i of arr) { someFn(arr[i]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map
for-of

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

for

418K/s

for-of

394K/s

foreach

160K/s

map

136K/s

View exact numbers

Test name	Executions per second
✓ for	417,786 Ops/sec
for-of	394,257 Ops/sec
foreach	160,458 Ops/sec
map	135,588 Ops/sec

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

LLMs can make mistakes. Check important info.

**What is being tested?**

The provided JSON represents a JavaScript microbenchmark that measures the execution time of different loop constructs on an array: `forEach`, `for` loops, `map`, and `for-of` loops.

**Options compared**

The benchmark compares four different approaches:

1. **forEach**: The `forEach` method is called on each element of the array, with a callback function that performs the desired operation.
2. **For loop**: A traditional `for` loop is used to iterate over the elements of the array, with an index variable `i` and a length variable `len`.
3. **Map**: The `map()` method is called on the array, which returns a new array with the results of applying the provided function to each element.
4. **For-of loop**: A `for...of` loop is used to iterate over the elements of the array, without an explicit index variable.

**Pros and Cons**

*   **forEach**: Pros: Simple to implement, efficient for small arrays. Cons: May not be as efficient as other methods for large arrays due to function call overhead.
*   **For loop**: Pros: Allows direct access to array elements, can be faster for large arrays. Cons: Requires manual indexing and length management, can be error-prone.
*   **Map**: Pros: Returns a new array with the results, efficient for large arrays. Cons: Creates an additional array, may not be suitable for small arrays where memory is a concern.
*   **For-of loop**: Pros: Concise, easy to read, and maintainable. Cons: May have slightly slower performance compared to traditional `for` loops.

**Library**

There is no library explicitly used in this benchmark. However, the `map()` method uses the built-in JavaScript array prototype methods.

**Special JS features or syntax**

The benchmark does not use any special JavaScript features or syntax other than the four loop constructs being tested.

index loop vs for-of loop vs foreach vs map (version: 0)

Comparing performance of: `foreach vs for vs map vs for-of`

Created: 7 years ago by: Guest

Go to the latest result

foreach

for

map

for-of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

index loop vs for-of loop vs foreach vs map (version: 0)

Comparing performance of: foreach vs for vs map vs for-of

Created: 7 years ago by: Guest

Go to the latest result

foreach

for

map

for-of

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `foreach vs for vs map vs for-of`