Benchmark: for loop vs. .map [2]

Script Preparation code:

// Create sample data
var array = [1,2,3,4,5,6,7,8,9,0];

var manipulateFn = num => {
	return num * 2 * 3;
}

Tests:

.map
var newArray = array.map( i => manipulateFn(i));
for loop
var newArray = []; var arrLength = array.length var i for (i=0; i<arrLength; i++) { newArray.push(manipulateFn(array[i])); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map
for loop

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month 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

Test name	Executions per second
.map	1351902.2 Ops/sec
for loop	649720.6 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):

LLMs can make mistakes. Check important info.

The benchmark in question compares the performance of two approaches to manipulate an array in JavaScript: using the `.map()` method and a traditional `for` loop.

### Test Cases Overview

1. **Using `.map()`**
   ```javascript
   var newArray = array.map(i => manipulateFn(i));
   ```
   This test applies the `.map()` method to the `array`. The `.map()` function creates a new array populated with the results of calling `manipulateFn` on every element in the original array.

2. **Using a `for` Loop**
   ```javascript
   var newArray = [];
   var arrLength = array.length;
   var i;
   for (i = 0; i < arrLength; i++) {
       newArray.push(manipulateFn(array[i]));
   }
   ```
   In this case, the `for` loop iterates over the `array`, applying `manipulateFn` to each element and pushing the result into a new array.

### Comparison of Approaches

**Pros of Using `.map()`:**
- **Clarity and Conciseness**: The code is more expressive and easier to read. Using `.map()` conveys that a transformation is taking place.
- **Functional Style**: It adheres to functional programming paradigms, promoting immutability and reducing side effects.

**Cons of Using `.map()`:**
- **Performance Overhead**: There may be performance overhead due to the requirement to create a new array and the internal function calls involved.

**Pros of Using a `for` Loop:**
- **Performance Efficiency**: The `for` loop might have better performance in some cases, especially for larger datasets, as it directly manipulates array elements without the overhead associated with function calls and intermediate array creation.
- **Control over Iteration**: The loop grants precise control over the iteration process (e.g., conditionally skipping elements).

**Cons of Using a `for` Loop:**
- **Verbosity**: The code can become verbose and less readable, especially with more complex operations, leading to potential mismanagement of the loop logic.
- **Mutation Risk**: Using a `for` loop increases the risk of inadvertently altering the original data or introducing side effects if not handled carefully.

### Other Considerations
- **Readability vs. Performance**: Choosing between these two approaches often boils down to a trade-off between code readability and performance. In many cases, especially for smaller arrays, the performance difference may be negligible, thus coding style and clarity might take precedence.
- **JavaScript Engine Optimizations**: Modern JavaScript engines like V8 (used in Chrome) have become optimized at handling both `.map()` and `for` loops, which makes real-world performance differences less pronounced in many instances.

### Alternatives
Other alternatives for manipulating arrays in JavaScript may include:
- **`.forEach()`**: Similar to `.map()`, but it's primarily used for side effects and does not return a new array.
- **`for...of` loops**: Provide a cleaner syntax for iterating over iterable objects like arrays.
- **Reduce**: Using `.reduce()` can also achieve similar results while being more versatile.

In conclusion, the choice between using `.map()` and a traditional `for` loop should consider both the specific needs of a project—such as array size, complexity, and the desired level of readability—as well as the team's preferred coding practices.

Related benchmarks:

for loop vs. .map [2] (version: 1)

Comparing performance of: .map vs for loop

Created: one month ago by: Guest

Jump to the latest result

.map

for loop

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one month ago):