var array = [1,2,3];
var d = array[2];
var z = array.at(2);
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
array[array.length - 1] | |
array.at(-1) |
Test name | Executions per second |
---|---|
array[array.length - 1] | 203063216.0 Ops/sec |
array.at(-1) | 203573744.0 Ops/sec |
Let's break down the provided benchmark and explain what is being tested, compared, and their pros/cons.
What is being tested:
The test case compares two ways to access the last element of an array in JavaScript:
array[array.length - 1]
: This method uses the square bracket notation ([]
) to access the array element at the specified index.array.at(-1)
: This method uses the at()
function (introduced in ECMAScript 2019) to access the array element at the specified index.Options compared:
The two options are being compared in terms of their performance and execution speed.
Pros/Cons of each approach:
array[array.length - 1]
:at()
method due to the use of square brackets.array.at(-1)
: (introduced in ECMAScript 2019)array[array.length - 1]
method due to its optimized implementation.Library/Functionality:
In this case, no external library or function is being compared. The at()
function is a built-in JavaScript method introduced in ECMAScript 2019.
Special JS feature/syntax:
The at()
function is an example of a modern JavaScript feature that allows for more expressive and efficient array indexing. It's designed to provide a better alternative to the traditional array[array.length - 1]
approach, especially when working with large arrays or arrays of objects.
Other considerations:
When choosing between these two approaches, consider the following factors:
at()
function support, you may want to stick with array[array.length - 1]
.at()
method might be a better choice.at()
more intuitive than using square brackets.Alternatives:
If you need to support older browsers that don't have built-in at()
function support or if you prefer not to use this modern JavaScript feature, other alternatives include:
get()
methodarray.get(index)
)However, these alternatives may come with additional complexity and potential performance overhead compared to the built-in at()
function.