Benchmark: for of vs for loops 4

Script Preparation code:

const planes = new Array(50_000).fill(1000);

Tests:

for-of
for (const plane of planes) { const a = plane + plane; }
for-index
for (let i = 0; i < planes.length; i++) { const plane = planes[i]; const a = plane + plane; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-of
for-index

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:137.0) Gecko/20100101 Firefox/137.0

Browser/OS: Firefox 137 on Windows

View result in a separate tab

Test name	Executions per second
for-of	4232.4 Ops/sec
for-index	22246.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated 3 days ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON compares two different approaches to iterating over an array of numbers in JavaScript: using a `for...of` loop and a traditional `for` loop that utilizes an index. The goal is to measure the performance of each iteration method when executing a simple operation on each element of an array.

### Options Compared

1. **`for-of` Loop**: This construct iterates directly over elements of the iterable (in this case, an array).
   ```javascript
   for (const plane of planes) {
       const a = plane + plane;
   }
   ```

2. **Traditional `for` Loop**: This approach uses an index to access each element of the array.
   ```javascript
   for (let i = 0; i < planes.length; i++) {
       const plane = planes[i];
       const a = plane + plane;
   }
   ```

### Performance Results

The benchmark results indicate the number of executions per second for each loop type:
- **`for-index` (Traditional `for` loop)**: 22,246 executions per second
- **`for-of`**: 4,232 executions per second

From these results, it is clear that the traditional `for` loop is significantly faster than the `for-of` loop in this scenario.

### Pros and Cons

#### `for-of` Loop
**Pros:**
- Simplicity: The syntax of `for-of` is concise and easy to read, particularly for those familiar with modern JavaScript.
- Can iterate over any iterable, not just arrays (like maps, sets, etc.).

**Cons:**
- Performance: Generally slower than traditional `for` loops, particularly in scenarios where optimization matters.
- Less control: No direct access to the iteration index, which can be a drawback for certain algorithms or manipulations.

#### Traditional `for` Loop
**Pros:**
- Performance: Typically faster due to lower overhead. Developers have more control over initialization, conditions, and increments.
- Direct access to the index, which can be useful for various operations.

**Cons:**
- Verbosity: More code is often required for setup (initialization, condition check, increment).
- More prone to errors; for instance, off-by-one errors can occur if the loop is not carefully constructed.

### Other Considerations

- **Context of Use**: While the traditional `for` loop performed better in this benchmark due to the simplicity of the operation, the choice of loop depends on the specific use case. For example, when iterating over complex data structures or requiring early exits, `for-of` may be more advantageous.
  
- **JavaScript Engine**: The performance of the loops can vary between JavaScript engines (V8, SpiderMonkey, etc.) and different browsers. Different environments may optimize loops differently, impacting performance in real-world situations.

### Alternatives

Other alternatives to consider include:
- **`forEach` Method**: This array method allows for iteration with a callback function, improving readability but often at the cost of performance due to function call overhead.
   ```javascript
   planes.forEach(plane => {
       const a = plane + plane;
   });
   ```

- **`map` Method**: If you're transforming data, using the `map` function can be more suitable and expressive. However, it creates a new array.
   ```javascript
   const results = planes.map(plane => plane + plane);
   ```

- **`reduce` Method**: This method is useful for accumulating results (like summation) but has different performance characteristics based on how it is used.
   ```javascript
   const total = planes.reduce((sum, plane) => sum + (plane + plane), 0);
   ```

Ultimately, the choice of loop type or approach can depend on factors such as performance requirements, readability, and the specific operations being performed on the data.

Related benchmarks:

for of vs for loops 4 (version: 2)

Comparing performance of: for-of vs for-index

Created: 3 days ago by: Registered User

Jump to the latest result

for-of

for-index

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 3 days ago):