const a = new Array(0)
const a = Array.from({ length: 0 })
const a = []
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
new Array() | |
Array.from() | |
[] |
Test name | Executions per second |
---|---|
new Array() | 6777215.0 Ops/sec |
Array.from() | 3081572.0 Ops/sec |
[] | 91561192.0 Ops/sec |
Let's break down the provided benchmark and explain what's being tested.
Benchmark Overview
The benchmark compares three different ways to create an empty array in JavaScript:
new Array()
Array.from({ length: 0 })
[]
Comparison of Options
Each option has its own pros and cons:
new Array()
: This method creates a new, empty array object. It's a simple and concise way to create an array. However, it can lead to unexpected behavior if the array is used as a primitive value (e.g., passed as an argument to String()
) or if it's not properly initialized.Array.from()
: This method creates a new array from an iterable source, such as an empty object with a length
property. It provides more flexibility than new Array()
and can handle more complex scenarios. However, it requires the source to be an object with a length
property, which might not always be available.[]
: This method creates an array literal by writing []
. It's simple and concise but can lead to confusion if the syntax is not well-known.Library Usage
None of the benchmark test cases explicitly use any libraries. However, Array.from()
uses the Array.prototype.from()
method, which is a part of the ECMAScript standard. The other two methods do not rely on any specific library.
Special JavaScript Features or Syntax
There are no special JavaScript features or syntax being tested in this benchmark.
Other Alternatives
Some alternative ways to create an empty array include:
Array()
: This method creates a new, empty array object. However, it's less common and less preferred than the other methods.void(0).slice()
: This method creates a new, empty array by calling slice()
on void(0)
, which returns an empty array.Array.create()
: This method is similar to new Array()
, but it's less common and less preferred.Benchmark Preparation Code
Since the benchmark preparation code is null, it means that the JavaScript engine is responsible for initializing the test environment, and the benchmarks are executed in a headless scenario without any external dependencies.