Benchmark: for vs foreach vs some vs for..of with modern var declarations

Script Preparation code:

var array = new Array(100);

Tests:

for
for (let i = 0; i < array.length; i++) { array[i]; }
foreach
array.forEach(function(i) { array[i]; });
some
array.some(function(i) { array[i]; });
for..of
for (const i of array) { array[i]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
for..of

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 23 days ago):

LLMs can make mistakes. Check important info.

The benchmark defined by the JSON provided compares the performance of different looping constructs in JavaScript: `for`, `forEach`, `some`, and `for..of`. Each of these constructs has different performance characteristics and use cases, and the benchmark aims to establish which is the fastest based on their execution speed in a controlled environment.

### Options Compared

1. **`for` loop**:
    - **Syntax**: `for (let i = 0; i < array.length; i++) { array[i]; }`
    - **Pros**: 
        - Highly performant as it involves minimal overhead.
        - Gives full control over loop mechanics (increment, index access, etc.).
    - **Cons**: 
        - More verbose and prone to off-by-one errors or other mistakes related to loop control.

2. **`forEach` method**:
    - **Syntax**: `array.forEach(function(i) { array[i]; });`
    - **Pros**:
        - Clean and readable syntax.
        - Automatically handles iterating over the array elements without explicit index management.
    - **Cons**:
        - Slightly slower than traditional loops due to the overhead of function calls.
        - Cannot be exited prematurely using `break` or `return`, which may limit its usability in certain scenarios.

3. **`some` method**:
    - **Syntax**: `array.some(function(i) { array[i]; });`
    - **Pros**:
        - Stops execution as soon as a condition is met (returns `true`), which can be more efficient when searching for a specific condition.
        - Provides a clean and expressive way to iterate over arrays when a boolean condition is being checked.
    - **Cons**:
        - Similar performance concerns as `forEach`, involving function call overhead.
        - May not be the best choice when needing to perform operations on every element since it's designed to terminate early on a true return.

4. **`for..of` loop**:
    - **Syntax**: `for (const i of array) { array[i]; }`
    - **Pros**:
        - Provides a simpler syntax for iterating over iterable objects.
        - Automatically retrieves the value of each element, improving readability.
    - **Cons**:
        - In this benchmark, it exhibits the slowest performance, likely due to the overhead of dealing with iterables and potential implications on how JavaScript engines optimize these loops.

### Summary of Results

From the latest benchmark results, the performance of the different loop constructs was measured in "Executions Per Second":

- **some**: 9,187,566.0 executions/sec
- **foreach**: 8,915,883.0 executions/sec
- **for..of**: 364,537.25 executions/sec
- **for**: 221,476.078125 executions/sec

The `some` method emerged as the fastest in this test, followed closely by `forEach`. Both of these methods leverage higher-level abstractions but incur additional overhead. The traditional `for` loop and `for..of` performed more poorly in this specific case, with `for..of` being the least efficient.

### Other Considerations and Alternatives

While this benchmark focuses on these specific looping constructs, there are additional alternatives and patterns available in JavaScript, such as:

- **Map and Reduce**: For transforming and aggregating array data, which might involve similar performance considerations but offer more expressive capabilities.
- **While or Do-While Loops**: These serve as alternatives for conditions-based iteration but are less commonly used for straightforward array traversal compared to the aforementioned methods.
- **Array methods** like `map`, `filter`, and `reduce` are also worth considering if the operation involves transformation or reduction of array data, though they have their own performance quirks due to the function calls involved.

Understanding when and why to choose a specific looping construct is crucial for optimizing performance-sensitive applications, especially in scenarios with large datasets or tight performance requirements.

Latest run results:

Run details: (Test run date: 23 days ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
for	221476.1 Ops/sec
foreach	8915883.0 Ops/sec
some	9187566.0 Ops/sec
for..of	364537.2 Ops/sec

Related benchmarks:

for vs foreach vs some vs for..of with modern var declarations (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some vs for..of

Created: 24 days ago by: Guest

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for

foreach

some

for..of

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated 23 days ago):