Benchmark: Loop methods - MeasureThat.net

Tests:

for
const arr = new Array(10000) for (let i = 0; i < arr.length; i++) { console.log(i); }
for len
const arr = new Array(10000) const len = arr.length for (let i = 0; i < len; i++) { console.log(i); }
while
let i = 0; const arr = new Array(10000) while (i < arr.length) { console.log(i); i++; }
while len
let i = 0; const arr = new Array(10000) const len = arr.length while (i < len) { console.log(i); i++; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
for len
while
while len

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/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for	47.2 Ops/sec
for len	47.1 Ops/sec
while	47.1 Ops/sec
while len	47.5 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided benchmark on MeasureThat.net is testing various looping methods in JavaScript to determine their performance in terms of execution speed. Below is a breakdown of each test case, the comparison of options, pros and cons, and considerations.

### Test Cases Explained

1. **For Loop**:
   ```javascript
   const arr = new Array(10000);
   for (let i = 0; i < arr.length; i++) {
       console.log(i);
   }
   ```
   - **Description**: This test measures the performance of a traditional `for` loop.
   - **Execution**: It initializes an array of size 10,000 and iterates through its elements using an index.

2. **For Loop with Length Caching**:
   ```javascript
   const arr = new Array(10000);
   const len = arr.length;
   for (let i = 0; i < len; i++) {
       console.log(i);
   }
   ```
   - **Description**: This test measures a `for` loop where the length of the array is stored in a variable (`len`).
   - **Execution**: Similar to the first test but optimized by caching the length to avoid accessing it in each iteration.

3. **While Loop**:
   ```javascript
   let i = 0;
   const arr = new Array(10000);
   while (i < arr.length) {
       console.log(i);
       i++;
   }
   ```
   - **Description**: This test assesses the performance of a `while` loop that continues until the condition is no longer true.
   - **Execution**: It checks the length of the array in the condition, which can result in accessing the property in each iteration.

4. **While Loop with Length Caching**:
   ```javascript
   let i = 0;
   const arr = new Array(10000);
   const len = arr.length;
   while (i < len) {
       console.log(i);
       i++;
   }
   ```
   - **Description**: A performance test for a `while` loop with cached length.
   - **Execution**: Avoids repeated access to the array's length property, similar to the optimizations in the `for` loop with length caching.

### Performance Comparison

The benchmark results show the number of executions per second for each method:

- **while len**: 47.46 executions/sec (fastest)
- **for**: 47.18 executions/sec
- **for len**: 47.09 executions/sec
- **while**: 47.07 executions/sec

### Pros and Cons of Different Approaches

1. **For Loop**:
   - **Pros**: Commonly understood and easy to use; straightforward syntax.
   - **Cons**: Might perform poorly if the array length is large due to repetitive property access in each iteration.

2. **For Loop with Length Caching**:
   - **Pros**: Better performance due to reduced overhead by caching the length.
   - **Cons**: Slightly more memory usage for the cached variable, but negligible in this context.

3. **While Loop**:
   - **Pros**: Can be more readable in certain contexts and avoids the complexity of maintenance in varied loop conditions.
   - **Cons**: Similar performance issues as the `for` loop, with repeated access to the array's length property.

4. **While Loop with Length Caching**:
   - **Pros**: Better performance by caching the length, similar to the optimized `for` version.
   - **Cons**: Same memory overhead concern, though minimal.

### Other Considerations

- **Console Logging**: All tests use `console.log()`, which may affect timing depending on the environment. This could skew benchmark results, as logging can be relatively slow.
- **Browser Variables**: The results may vary by browser iteration and optimization levels, especially with the JavaScript engine optimizations in different environments.

### Alternatives

- **`Array.forEach()`**: A method that executes a provided function once for each array element. This can be cleaner and more readable but is generally slower than traditional loops for performance-critical applications.
- **`for...of` Loop**: A newer iteration syntax that provides a simpler way to iterate over iterables but can have slight performance drawbacks compared to traditional loops in critical scenarios.
- **Functional Programming Constructs**: Functions like `map`, `filter`, and `reduce`, though often less performant for large datasets compared to traditional loops, they offer elegant and expressive coding patterns.

In summary, for intensive operations on arrays, the `for` loop with length caching and the `while` loop with length caching tend to perform better. Meanwhile, readability and maintainability are crucial factors when choosing loop types, so the best option can vary based on specific project requirements.

Related benchmarks:

Loop methods (version: 1)

Comparing performance of: for vs for len vs while vs while len

Created: one month ago by: Registered User

Jump to the latest result

for

for len

while

while len

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):