Benchmark: for vs forEach - MeasureThat.net

Script Preparation code:

var testArray = [];

for (var i = 1; i <= 10000; i++) {
   testArray.push(i);
}

Tests:

for loop
for(var i = 0, length = testArray.length; i < length; i += 1) { 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 the provided benchmark and explain what is being tested.

**Benchmark Overview**

The benchmark compares the performance of three JavaScript loops: `for`, `forEach`, and `map`. The goal is to determine which loop is the fastest for incrementing elements in an array.

**Script Preparation Code**

The script preparation code creates an empty array `testArray` with 10,000 elements using a simple `for` loop:
```javascript
var testArray = [];
for (var i = 1; i <= 10000; i++) {
  testArray.push(i);
}
```
This code sets up the input data for the benchmark.

**Html Preparation Code**

There is no HTML preparation code provided, which suggests that this benchmark only tests JavaScript performance and not DOM-related tasks.

**Individual Test Cases**

The benchmark includes three individual test cases:

1. **`for loop`**: This test case uses a traditional `for` loop to increment elements in the `testArray`.
```javascript
for (var i = 0, length = testArray.length; i < length; i += 1) {
  testArray[i] += 1;
}
```
2. **`forEach`**: This test case uses the `forEach` method to iterate over the `testArray` and increment elements.
```javascript
testArray.forEach((item) => {
  item += 1;
});
```
3. **`Map`**: This test case uses the `map` method to create a new array with incremented elements from the original `testArray`.
```javascript
testArray.map((item) => {
  item += 1;
});
```
**Library and Purpose**

There are no external libraries used in this benchmark.

**Special JS Feature or Syntax**

The `forEach` method is not considered special, as it's a built-in JavaScript array method. However, the use of `map` might be worth noting for developers familiar with functional programming concepts.

**Pros and Cons of Each Approach**

Here's a brief summary of the pros and cons of each approach:

* **`for` loop**:
	+ Pros: Simple, easy to understand, and performance-friendly.
	+ Cons: Can be error-prone if not used carefully, and may have slower iteration speeds compared to `forEach`.
* **`forEach`**:
	+ Pros: Concise, readable, and efficient for simple iteration tasks.
	+ Cons: May have slower iteration speeds compared to traditional `for` loops, and can be less efficient for large datasets due to the overhead of function invocation.
* **`Map`**:
	+ Pros: Can simplify code and reduce memory allocation, as it returns a new array with modified elements.
	+ Cons: May have slower performance due to the overhead of creating a new array, and may not be suitable for all use cases.

**Other Alternatives**

If you're looking for alternative methods to test iteration performance, consider using:

* **`reduce()`**: Similar to `forEach`, but uses accumulator values to reduce the array to a single value.
* **`filter()`**: Tests filtering performance by removing elements from the array based on a condition.
* **`every()`** and **`some()`**: Test predicate-based iteration by iterating over the array and evaluating conditions for each element.

Keep in mind that these alternatives may introduce additional complexity or overhead, so choose them judiciously depending on your specific use case.

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):