Benchmark: Empty Array - New vs Static

Script Preparation code:

function execute(fn, arr) {
  for(var i = 0; i < 1000000; i++) {
    fn(arr)
  }
}

Tests:

New
function mapValues(arr) { return (arr || []).map(x => x + 1) } execute(mapValues, null)
Static
const staticEmpty = [] function mapValues(arr) { return (arr || staticEmpty).map(x => x + 1) } execute(mapValues, null)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
New
Static

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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

LLMs can make mistakes. Check important info.

Let's break down the provided JSON and explain what's being tested.

**Benchmark Definition**

The benchmark is comparing two approaches to create an empty array: using the `new` operator versus using a static variable.

1. **New Operator**: The script preparation code creates a new function `execute` that takes another function `fn` as an argument, which applies the `mapValues` function to an empty array created with the `new` operator.
2. **Static Variable**: The script preparation code creates a constant `staticEmpty` variable, which holds an empty array. The same `execute` function is used, but it uses this static variable instead of creating a new one.

**Options Compared**

The two options being compared are:

1. Creating an empty array using the `new` operator.
2. Creating an empty array as a constant variable.

**Pros and Cons**

Using the `new` operator to create an empty array has some implications:

Pros:

* **Efficiency**: In modern JavaScript engines, creating an empty array with `new` is often more efficient than creating one with `[]`.
* **Memory allocation**: When using `new`, the engine allocates memory for a new object, which can be beneficial for certain use cases.

Cons:

* **Overhead**: Creating an empty array with `new` might incur some overhead due to the creation of a new object.
* **Inconsistent behavior**: In some older browsers or environments, creating an empty array with `new` might not behave as expected.

Using a static variable to create an empty array has its own set of implications:

Pros:

* **Efficiency**: Creating an empty array as a constant variable is generally faster than using the `new` operator.
* **Caching**: If the same static variable is used across multiple executions, it can be cached by the engine, reducing overhead.

Cons:

* **Memory allocation**: When using a static variable, memory is allocated only once when the variable is defined. If this variable is reused across different contexts, there might be unexpected behavior.
* **Variable scope**: The use of a static variable means that it's accessible throughout the entire execution context, which can lead to unintended side effects.

**Library and Special JS Features**

There are no libraries used in these benchmarks. However, JavaScript engines have some special features and optimizations that might affect performance:

* **Call stack optimization**: Modern JavaScript engines like V8 (used by Chrome) optimize call stacks for better performance. This might impact the results of this benchmark.
* **Dead code elimination**: Engines eliminate dead code to improve performance. This could potentially reduce the overhead of using `new` or a static variable.

**Other Considerations**

When interpreting these results, keep in mind that:

* The benchmark is run on a desktop environment with Chrome 116 and a specific hardware configuration.
* The number of executions per second (ExecutionsPerSecond) is used to measure performance. A higher value indicates better performance.
* There might be variations in results across different browsers or environments.

**Alternatives**

Other alternatives for creating an empty array include:

1. Using the `[]` syntax directly: `const arr = [];`
2. Using a library like Lodash, which provides the `isEmpty` function to check if an array is empty.
3. Using other specialized functions or methods provided by the JavaScript engine itself.

Keep in mind that these alternatives might have different performance characteristics and trade-offs compared to using the `new` operator or a static variable.

Related benchmarks:

Empty Array - New vs Static (version: 0)

Comparing performance of: New vs Static

Created: 2 years ago by: Guest

Jump to the latest result

New

Static

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):