Benchmark: Array population test

Script Preparation code:

var arraySize = 10000;
var iterations = arraySize + 100;
var data;
var operate = function(){
  for(var index = 0; index < iterations; index++){
     data.unshift({});
    if(data.length > arraySize) data.pop();
  }
}

Tests:

new Array
data = new Array(arraySize); operate();
brackets
data = []; operate();
brackets with length
data = []; data.length=arraySize; operate();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array
brackets
brackets with length

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 dive into the explanation.

**Benchmark Definition JSON Analysis**

The provided benchmark definition represents a test for populating an array in JavaScript. Here, we have three variations:

1. **new Array**: This creates a new array using the `new` keyword and initializes it with zeros.
2. **brackets**: This uses square brackets `[]` to create an empty array.
3. **brackets with length**: This sets the initial length of the array before creating it.

The script preparation code defines a function `operate()` that populates the array by unshifting objects onto it, removing elements if the length exceeds the initial array size (`arraySize`). The goal is to measure how these different approaches impact performance.

**Options Compared**

We have two primary options being compared:

* **new Array**: Using the `new` keyword to create an array.
* **brackets**: Using square brackets `[]` to create an empty array.
* **brackets with length**: Setting the initial length of the array before creating it.

Each option has its pros and cons:

* **new Array**:
	+ Pros: Can be faster for large arrays due to the optimized array creation process in modern browsers.
	+ Cons: May have a higher overhead for smaller arrays, as the `new` keyword involves additional function calls.
* **brackets**:
	+ Pros: Generally faster and more lightweight than using the `new` keyword.
	+ Cons: Requires careful attention to ensure the brackets are properly closed, which can lead to errors if not done correctly.
* **brackets with length**:
	+ Pros: Can be beneficial for reducing overhead when working with arrays of known size.
	+ Cons: May introduce additional complexity and potential performance overhead due to the initial length setting.

**Library Used (None)**

In this benchmark, no specific JavaScript library is used. The script preparation code and individual test cases rely solely on built-in JavaScript functionality.

**Special JS Feature/Syntax (None)**

There are no special JavaScript features or syntax being tested in this benchmark.

**Benchmark Result Analysis**

The latest benchmark result shows the executions per second for each test case across a few different browsers:

* **brackets**: 56.857 executions per second
* **new Array**: 32.483 executions per second
* **brackets with length**: 23.600 executions per second

These results suggest that, in this specific scenario, using brackets `[]` for array creation yields the best performance.

**Other Alternatives**

If you're interested in exploring alternative approaches, here are a few options:

* Using the `Array()`, `ArrayConstructor`, or `Array.prototype` methods instead of `new Array`.
* Employing custom array creation functions.
* Utilizing third-party libraries like Lodash or Underscore.js for array operations.

Keep in mind that these alternatives may introduce additional complexity, performance overhead, or errors, so it's essential to carefully evaluate their suitability for your specific use case.

Related benchmarks:

Array population test (version: 0)

Comparing performance of: new Array vs brackets vs brackets with length

Created: 9 years ago by: Guest

Jump to the latest result

new Array

brackets

brackets with length

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):