Benchmark: Array.fill vs Array.from with dyamnic data

Tests:

Array.fill
new Array(200000).fill({ a: 1}).map(function(value, index) { return {...value, id: index}})
Array.from
Array.from({length: 200000}, function(_v, index) { return { a: 1, id: index}})

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.fill
Array.from

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/117.0.0.0 Safari/537.36

Browser/OS: Chrome 117 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Array.fill	116.8 Ops/sec
Array.from	139.2 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is designed to compare two approaches for creating an array of objects with dynamic data: `Array.fill` and `Array.from`. The benchmark definition provides both methods, but they differ in their input data. For `Array.fill`, a new array of 200,000 elements is created using the `fill()` method, while for `Array.from`, an object with a length of 200,000 is used as the input.

**Options Compared**

The two options being compared are:

1. **`Array.fill()`**: A method that creates a new array by repeating the provided value (in this case, an object with `a: 1`) to fill the entire array.
2. **`Array.from()`**: A method that creates a new array from an iterable or an array-like object (in this case, the object with a length of 200,000).

**Pros and Cons**

Here are some pros and cons of each approach:

* **`Array.fill()`**:
	+ Pros: Faster execution, potentially more efficient for large arrays.
	+ Cons: Can be slower for small arrays or when the fill value is complex, as it needs to create a new object for each element. Additionally, it can lead to memory issues if the array is too large.
* **`Array.from()`**:
	+ Pros: More flexible and efficient for creating arrays from existing objects or iterables, especially when working with small to medium-sized datasets.
	+ Cons: Can be slower than `Array.fill()` for very large arrays.

**Library**

Neither of these options uses a library. They are built-in methods in JavaScript.

**Special JS Feature/Syntax**

There is no special JS feature or syntax used in this benchmark. It's purely focused on comparing the performance of two built-in methods.

**Other Considerations**

When running benchmarks like this, it's essential to consider factors that might affect performance, such as:

* Garbage collection: In modern JavaScript engines, garbage collection can introduce pauses and affect performance.
* Memory allocation: Creating large arrays or objects can lead to memory allocation issues, which might impact performance.

**Alternatives**

If you're looking for alternatives to `Array.fill()` and `Array.from()`, consider the following options:

* **`Array.prototype.map()`**: While not suitable for creating an array of fixed-size elements, it's often used in conjunction with other methods (like `fill()` or `from()`) to process arrays.
* **`Array.prototype.reduce()`**: Similar to `map()`, but it's more commonly used for aggregation and processing.

For creating arrays from existing iterables, consider using libraries like Lodash (`_.times()`) or Ramda (`ramda.times()`). However, keep in mind that these libraries add overhead, so be cautious when including them in performance-critical code.

Related benchmarks:

Array.fill vs Array.from with dyamnic data (version: 0)

Comparing performance of: Array.fill vs Array.from

Created: one year ago by: Guest

Jump to the latest result

Array.fill

Array.from

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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