Benchmark: Array.map vs preallocation ckck

Tests:

Map
const array2 = new Array(1000000).map((item, index) => index);
Preallocation
const array2 = new Array(1000000); for (let i = 0; i < array2.length; i++) array2[i] = i;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map
Preallocation

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Map	109.3 Ops/sec
Preallocation	325.7 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the explanation into manageable chunks.

**Benchmark Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The benchmark in question compares two approaches for creating an array: using `Array.prototype.map()` (referred to as "Map") versus preallocating the array and then filling it with values (referred to as "Preallocation").

**Options Compared**

Two options are being compared:

1. **Map**: Using the `Array.prototype.map()` method, which creates a new array by applying a provided function to each element of an existing array.
2. **Preallocation**: Creating a new array with a fixed length and then filling it with values using a loop.

**Pros and Cons**

Here are some pros and cons of each approach:

**Map:**

Pros:

* More concise code, as the `map()` method can be used to create the entire array in one step.
* Less memory usage, as the new array is created only when needed.

Cons:

* May incur additional overhead due to the creation of a new array and the execution of the provided function for each element.
* Performance may degrade if the provided function is computationally expensive or creates a large number of temporary objects.

**Preallocation:**

Pros:

* Can provide better performance, as the preallocated array can be filled with values in a single loop iteration.
* Can reduce memory usage by reusing the existing array.

Cons:

* Requires more code, as an additional loop is needed to fill the array with values.
* May require more memory upfront, depending on the length of the array and the amount of data being stored.

**Library**

There is no specific library mentioned in this benchmark. However, `Array.prototype.map()` is a built-in method in JavaScript, which means that any browser or environment that supports JavaScript should be able to execute it without additional libraries or dependencies.

**Special JS Feature/Syntax**

The only special syntax used in this benchmark is the use of arrow functions (`=>`) within the `map()` method. Arrow functions are a shorthand way of defining small, single-expression functions in JavaScript and were introduced in ECMAScript 2015 (ES6).

**Other Alternatives**

If you're looking for alternative approaches to create an array in JavaScript, here are some options:

* Using `Array.from()`: This method creates a new array from an iterable object or an array-like object.
* Using a custom function: You could write a custom function to create the array, but this would likely be less efficient and more verbose than using `map()` or preallocation.

**Benchmark Preparation Code**

The benchmark preparation code is empty in this case, which means that the user needs to provide their own script or HTML code to execute the benchmark. This allows users to compare the performance of different approaches with their own specific use cases.

I hope this explanation helps!

Related benchmarks:

Array.map vs preallocation ckck (version: 0)

Comparing performance of: Map vs Preallocation

Created: 2 years ago by: Guest

Jump to the latest result

Map

Preallocation

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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