Benchmark: Fastest iteration over array: map vs forEeach vs while vs for loop

Script Preparation code:

window.arr = [1, "two", 3, "four", 5, {"sixth": 6}, 7, 8, 9, "ten"];

Tests:

for loop
for (let i = 0; i < 0; i++) console.log(arr[i]);
forEach
arr.forEach(el => console.log(el));
map
arr.map(el => console.log(el));
while
let i = 0; while (i < arr.length) { console.log(arr[i]); i++; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop
forEach
map
while

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:95.0) Gecko/20100101 Firefox/95.0

Browser/OS: Firefox 95 on Windows

View result in a separate tab

Test name	Executions per second
for loop	1152259456.0 Ops/sec
forEach	9745.3 Ops/sec
map	9650.7 Ops/sec
while	9767.4 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**
The provided benchmark definition measures which approach is the fastest for iterating over an array in JavaScript. The options being compared are:

1. **For loop**: A traditional loop that uses a counter variable to iterate over the array elements.
2. **While loop**: A loop that continues as long as a condition is true, used here with `i < arr.length`.
3. **forEach**: An array method that executes a callback function for each element in the array.
4. **Map**: An array method that creates a new array with the results of applying a provided function to each element in the original array.

**Options Comparison**

*   **For loop vs While loop**: Both loops have a similar performance, but the while loop might be slightly faster due to its ability to stop iterating as soon as the condition is false. However, this difference is usually negligible.
*   **forEach vs Map**: The `forEach` method and the map function are essentially doing different things. The `forEach` method executes the callback function for each element in the array without returning any value, while the map function creates a new array with the results of applying the provided function to each element in the original array. In terms of performance, the map function might be slightly faster because it can take advantage of the optimized C++ implementation under the hood.
*   **For loop vs Map**: The for loop and the map function are both iterating over the array elements, but the map function creates a new array with the results, while the for loop simply logs each element. In terms of performance, the for loop might be slightly faster because it doesn't involve creating a new array.

**Pros and Cons**

*   **For loop**: Pros - simple to understand and implement, can be used in various contexts. Cons - may not be as efficient as other options.
*   **While loop**: Pros - can stop iterating earlier if the condition is false. Cons - might be slightly slower than the for loop due to the overhead of comparing the counter variable with the array length.
*   **ForEach**: Pros - easy to use and implement, suitable for cases where you don't need to return any value. Cons - may not be as efficient as other options because it involves creating an event loop.
*   **Map**: Pros - creates a new array with optimized performance. Cons - might not be necessary in all cases.

**Library and Special Features**

There are no libraries or special JavaScript features mentioned in the benchmark definition. The focus is on comparing the basic iteration approaches provided by the standard JavaScript language.

**Other Alternatives**
If you're looking for alternative methods to iterate over arrays, consider:

*   **Using `for...in` loop**: This loop iterates over the array's index and key pairs.
*   **Using `reduce()` method**: This method reduces an array to a single value by applying a provided function on each element in the array.
*   **Using `filter()` method**: This method creates a new array with all elements that pass the test implemented by the provided function.

**In conclusion**

The benchmark results provide valuable insights into which iteration approach is the fastest for your specific use case. Take note of the pros and cons of each option and consider factors such as performance, readability, and maintainability when choosing an approach.

Related benchmarks:

Fastest iteration over array: map vs forEeach vs while vs for loop (version: 0)

Comparing performance of: for loop vs forEach vs map vs while

Created: 3 years ago by: Guest

Jump to the latest result

for loop

forEach

map

while

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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