Benchmark: For Each Vs Map Example Medium

Script Preparation code:

// Create sample data
var array = [];
array.forEach( i => array.push(i) );

var manipulateFn = num => {
	return num * 2 * 3;
}

Tests:

.map
var newArray = array.map( i => manipulateFn(i));
.forEach
var newArray = []; array.forEach( i => { newArray.push(manipulateFn(i)); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
.map
.forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/141.0.0.0 Safari/537.36 Edg/141.0.0.0

Browser/OS: Chrome 141 on Windows

View result in a separate tab

Test name	Executions per second
.map	120584008.0 Ops/sec
.forEach	122588064.0 Ops/sec

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's being tested.

**Benchmark Overview**

MeasureThat.net provides a platform for JavaScript microbenchmarks. The provided benchmark measures the performance difference between using the `map` method versus the `forEach` loop to perform a simple arithmetic operation on an array of numbers.

**Script Preparation Code**

The script preparation code generates an empty array `array` and then uses `forEach` to push a manipulated number into the array:
```javascript
// Create sample data
var array = [];
array.forEach(i => array.push(i));
```
This code prepares the input data for the benchmark.

**Html Preparation Code**

There is no HTML preparation code provided, which means that the benchmark focuses solely on JavaScript performance without considering any additional factors like rendering or DOM manipulation.

**Test Cases**

The benchmark consists of two test cases:

1. **`.map`**: The first test case uses the `map` method to create a new array with the manipulated numbers:
```javascript
var newArray = array.map(i => manipulateFn(i));
```
2. **`.forEach`**: The second test case uses a `forEach` loop to push the manipulated numbers into a new array:
```javascript
var newArray = [];
array.forEach(i => {
  newArray.push(manipulateFn(i));
});
```
**Library: `manipulateFn`**

The `manipulateFn` function is a simple arithmetic operation that takes a number as input and returns its product multiplied by 2 and 3:
```javascript
var manipulateFn = num => {
  return num * 2 * 3;
}
```
This library is used in both test cases to simulate the actual work being performed.

**Special JS Feature: Closures**

The `forEach` loop uses a closure to capture the outer scope's variables, including `array`. This is an advanced JavaScript feature that can affect performance. However, since the benchmark focuses solely on the iteration method and not on other aspects of the code, this feature is not explicitly mentioned.

**Pros and Cons of Different Approaches**

Here are some pros and cons of using `map` versus `forEach`:

* **`.map`**:
	+ Pros: Efficient and concise way to create a new array with transformed elements.
	+ Cons: Can be less readable, especially for large datasets or complex transformations.
* **`.forEach`**:
	+ Pros: Can be more readable and easier to maintain, as it allows for side effects (e.g., pushing elements into an array).
	+ Cons: Typically slower than `map` due to the overhead of function calls and loops.

**Alternatives**

Other alternatives to `map` and `forEach` include:

* **`.reduce()`**: A method that reduces an array to a single value by applying a reduction function to each element.
* **Array.prototype.filter()`: Removes elements from an array based on a condition.
* **Caching or memoization**: Storing intermediate results or computing values only when necessary to avoid redundant computations.

Keep in mind that the choice of iteration method depends on the specific use case and performance requirements.

Related benchmarks:

For Each Vs Map Example Medium (version: 0)

Comparing performance of: .map vs .forEach

Created: 7 years ago by: Guest

Jump to the latest result

.map

.forEach

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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