Benchmark: new Array() vs Array.from() with random data

Tests:

new Array(1000)
new Array(1000).fill(0).map(() => Math.random())
Array.from({length: 1000})
Array.from({length: 1000}, () => Math.random())

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
new Array(1000)
Array.from({length: 1000})

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The provided benchmark measures the performance difference between creating an array using `new Array()` versus using `Array.from()` with random data.

**What is being tested?**

Two test cases are compared:

1. Creating an array of 1000 elements using `new Array(1000).fill(0).map(() => Math.random())`.
2. Creating an array of 1000 elements using `Array.from({length: 1000}, () => Math.random())`.

**Options being compared**

The two approaches are compared in terms of their performance, which is measured by the number of executions per second.

**Pros and Cons of each approach**

1. **Using `new Array()`**:
	* Pros:
		+ This method creates a new array with a specific length, which can be useful when the length is known beforehand.
	* Cons:
		+ It involves additional overhead due to the creation of an array, which may not be necessary if only a few elements are needed.
2. **Using `Array.from()`**:
	* Pros:
		+ This method creates an array with a specific length and fills it with values in a single operation, which can be more efficient than using `new Array()`.
	* Cons:
		+ It requires the creation of an object with a `length` property, which may not be necessary if only an array is needed.

**Library used**

In this benchmark, no specific library is used beyond what is built-in to JavaScript. However, it's worth noting that `Array.from()` was introduced in ECMAScript 2015 (ES6) as part of the standard library.

**Special JavaScript features or syntax**

None are mentioned in this benchmark. Both test cases use basic JavaScript syntax and do not rely on any advanced features or libraries beyond what is built-in to JavaScript.

**Other alternatives**

There are other ways to create arrays in JavaScript, such as using a `for` loop:

```javascript
const arr = new Array(1000);
for (let i = 0; i < 1000; i++) {
  arr[i] = Math.random();
}
```

Or using `Array.prototype.fill()` and `Math.random()`:

```javascript
const arr = new Array(1000).fill(0).map(() => Math.random());
```

However, these approaches are not what the benchmark is comparing (i.e., `new Array()` vs. `Array.from()`)

Latest run results:

Run details: (Test run date: 6 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Windows

View result in a separate tab

Test name	Executions per second
new Array(1000)	5220.2 Ops/sec
Array.from({length: 1000})	3459.3 Ops/sec

Related benchmarks:

new Array() vs Array.from() with random data (version: 0)

Comparing performance of: new Array(1000) vs Array.from({length: 1000})

Created: one year ago by: Guest

Jump to the latest result

new Array(1000)

Array.from({length: 1000})

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):