Benchmark: for vs forEach - MeasureThat.net

Script Preparation code:

var testArray = [];

for (var i = 1; i <= 100; i++) {
   testArray.push(i);
}

Tests:

for loop
for(var i = testArray.length; i>0; i--) { testArray[i] += 1; }
forEach
testArray.forEach((item) => { item += 1; });
Map
testArray.map((item) => { item += 1; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for loop
forEach
Map

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in the provided benchmark.

The main goal of this benchmark is to compare the performance of three different approaches for iterating over an array:

1.  **For Loop**: A traditional loop that uses a counter variable (`i`) to iterate over the elements of the array.
2.  **ForEach**: The `forEach` method, which is a built-in JavaScript function that executes a callback function once for each element in an array.
3.  **Map**: The `map` method, which also applies a transformation to each element in an array and returns a new array.

The benchmark measures the number of executions per second (`ExecutionsPerSecond`) for each approach on different browsers (in this case, Chrome 64) with various device platforms (Other) and operating systems (Windows).

Now, let's discuss the pros and cons of each approach:

**For Loop**

Pros:

*   **Control**: For loops give you direct control over the iteration process, allowing you to skip elements or perform operations in a specific order.
*   **Performance**: In some cases, for loops can be faster due to the overhead of JavaScript's built-in loop methods.

Cons:

*   **Error-prone**: For loops require manual index management, which can lead to bugs and errors if not handled correctly.
*   **Limited parallelization**: For loops cannot be easily parallelized, as each iteration is executed sequentially.

**ForEach**

Pros:

*   **Concise syntax**: The `forEach` method provides a concise way to iterate over arrays without manual index management.
*   **Parallelization**: JavaScript's built-in loop methods can be optimized for parallel execution, making `forEach` suitable for performance-critical code.

Cons:

*   **Performance overhead**: `forEach` incurs additional overhead due to the creation of temporary objects and the handling of callback functions.
*   **Limited control**: The `forEach` method does not provide direct control over the iteration process, which can limit its flexibility in certain scenarios.

**Map**

Pros:

*   **Concise syntax**: Similar to `forEach`, the `map` method provides a concise way to perform transformations on arrays without manual index management.
*   **Parallelization**: Like `forEach`, `map` can be optimized for parallel execution, making it suitable for performance-critical code.

Cons:

*   **Performance overhead**: The `map` method also incurs additional overhead due to the creation of temporary objects and the handling of callback functions.
*   **Less control**: The `map` method does not provide direct control over the iteration process, which can limit its flexibility in certain scenarios.

In general, for loops are suitable when:

*   You require direct control over the iteration process.
*   You need to perform operations on elements in a specific order or skip elements altogether.

On the other hand, `forEach` and `map` are better choices when:

*   You want a concise way to iterate over arrays without manual index management.
*   You prioritize parallelization and performance optimization.

Now, regarding special JS features or syntax used in this benchmark, there is no explicit mention of any advanced JavaScript features. However, the use of built-in methods like `forEach` and `map` indicates that the benchmark is designed to take advantage of these optimized functions.

Related benchmarks:

for vs forEach (version: 0)

Comparing performance of: for loop vs forEach vs Map

Created: 8 years ago by: Guest

Jump to the latest result

for loop

forEach

Map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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