Benchmark: comparing for vs map vs forEach methods

Script Preparation code:

// Create sample data
var array = [1,2,3,4,5,6,7,8,9,0];

var manipulateFn = num => {
	return num * 2 * 3;
}

Tests:

for
var newArray = []; for(var i=0; i < array.length; i++) { newArray.push(manipulateFn(i)); };
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
for
map
forEach

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**What is tested?**

The provided JSON benchmark measures the performance of three different approaches to manipulate an array:

1.  **For loop**: A traditional `for` loop that iterates over the array elements and pushes each element multiplied by a certain function (`manipulateFn`) into a new array.
2.  **Map method**: The `map()` method, which creates a new array with the results of applying the provided function to every element in the original array.
3.  **ForEach loop**: A modern `forEach` loop that iterates over the array elements and pushes each element multiplied by the same function into a new array.

**Options compared**

The benchmark compares these three approaches:

*   For loop
*   Map method
*   ForEach loop

These options are compared to determine which approach is most efficient in terms of performance.

**Pros and Cons of different approaches:**

1.  **For loop**: Traditional `for` loops can be more control-oriented, as the developer has direct access to the iteration variables. However, they might not provide the same level of abstraction or conciseness as other methods.
2.  **Map method**: The `map()` method is a concise and expressive way to create new arrays by applying a function to each element in an existing array. It's also more memory-efficient since it doesn't require creating an intermediate array. However, it may have performance overhead due to the creation of an additional array.
3.  **ForEach loop**: The modern `forEach` loop is often used for its clarity and conciseness when iterating over arrays. Similar to `map()`, it's more concise than a traditional `for` loop and doesn't require creating an intermediate array. However, some older browsers may not support this method.

**Libraries and their purpose:**

The benchmark code uses the built-in JavaScript functions:

*   `Array.prototype.map()` - creates a new array with the results of applying the provided function to every element in the original array.
*   `Array.prototype.forEach()` - executes a function once for each array element, without returning any value.

These functions are part of the ECMAScript standard and do not require external libraries to work.

**Special JavaScript feature:**

The benchmark code uses modern JavaScript syntax, specifically:

*   The arrow function (`i => manipulateFn(i)`) is used in the `map()` method.
*   The concise syntax of the `forEach` loop.

These features are widely supported by most modern browsers and do not require any external libraries to work.

**Other alternatives:**

If you were to reimplement this benchmark using other approaches, here are some alternatives:

1.  **Using a custom loop**: You could create your own loop function that manually iterates over the array elements.
2.  **Using `Array.prototype.reduce()`**: This method can be used to accumulate values in an array while iterating over it.
3.  **Using `Array.prototype.filter()`, `Array.prototype.some()`, or other aggregate methods**: Depending on the specific requirements of your benchmark, you might use these methods instead.

However, keep in mind that these alternatives might not provide the same level of performance as the original code using built-in JavaScript functions like `map()` and `forEach`.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36

Browser/OS: Chrome 70 on Linux

View result in a separate tab

Test name	Executions per second
for	527579.2 Ops/sec
map	945497.1 Ops/sec
forEach	518576.9 Ops/sec

Related benchmarks:

comparing for vs map vs forEach methods (version: 0)

Comparing performance of: for vs map vs forEach

Created: 5 years ago by: Registered User

Jump to the latest result

for

map

forEach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 24 days ago):