If you have worked with JavaScript arrays before, you might know that they can be destructured much like objects. This is most commonly used to extract the first value of an array or the values of an array with a known length.
But destructuring can go much further, as it allows you to extract the length
property of an array. Add this to the fact that extracted variables can be used in the destructuring assignment itself and you can put together a one-liner to extract the last element of an array.
const arr = [1, 2, 3];
const { 0: first, length, [length - 1]: last } = arr;
first; // 1
last; // 3
length; // 3
While this technique is interesting, it has a couple of caveats. First off, you have to extract the length
property, which creates an additional variable for it. And secondly, it doesn't have any significant performance advantages over other options, such as using Array.prototype.slice()
.
Snippet collection
A collection of quick tips and tricks to level up your coding skills one step at a time.
JavaScript, Array
Returns the symmetric difference between two arrays, after applying the provided function to each array element of both.
JavaScript, Array
Returns the difference between two arrays, after applying the provided function to each array element of both.
JavaScript, Array
Executes a provided function once for each array element, starting from the array's last element.