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Get last element of array in JavsScript

vickyktk on January 18, 2022

Whatever the programming language you code in ,I am sure you will be playing with arrays every day. So today we will be looking at options we can g...
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giokhar profile image
Giorgi Kharshiladze •

I think you are missing one of the methods that was added not too long ago.
Array.prototype.at(). To get the last element in an array you can do myArr.at(-1).
developer.mozilla.org/en-US/docs/W...

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vickyktk •

Oh Yes !!! Thank You. This pretty usefull and easy

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Daniel Gropp •

While it’s a cool new method, keep in mind that currently it’s not supported in Safari based devices.

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Alex Lohr •

You can easily polyfill it:

if (![].at) {
  Array.prototype.at = function(pos) { return this.slice(pos, pos + 1)[0] }
}
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Nicolas Bouvrette •

This won't work with negative values.

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Wojciech •

In Safari Technology Preview you can activate it via Develop > Experimental Features

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Jon Randy 🎖️ •

A somewhat unusual way:

const str = 'Hello'
const {length, [length-1]: last} = str

console.log(last) // 'o'
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Wojciech •

Using console.log in prod is discouraged

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Jon Randy 🎖️ •

Naked flames in firework factories are discouraged too

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labspl profile image
Wojciech •

Laugh all you want, but console.log can be abused by some threat actors very easily. I mean, output of console.log is not escaped ( or otherwise secured ) in any way

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Jon Randy 🎖️ •

I'm not laughing, but your comment was entirely irrelevant. The console.log I used was simply used to display the result of some sample code - in a similar way to the way the original poster used it. No-one is suggesting in any way that it should be used in production code.

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labspl profile image
Wojciech • • Edited

OK. So imagine this:

How are web-enabled systems attacked? Of course there are many ways, but first and the most used one method of probing is through reverse engineering output of console.log.

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GrahamTheDev •

The console.log is for demonstration purposes, you can just do:

let myNewVar = last

and then return it or use it or whatever, the only bit that is of significance is:

const {length, [length-1]: last} = str

Which I am still processing as Jon always blows my mind with some weird syntax I haven't seen before (or more precisely have seen but don't use so have to then go and do a load of unpacking of his solution 🤣)!

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Jon Randy 🎖️ • • Edited

@labspl - I'm not disagreeing with you, but - again - this is entirely irrelevant to the post, or to my original comment

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Jon Randy 🎖️ •

@inhuofficial I aim to please :)

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jzombie •

This is awesome

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meirlamdan • • Edited

what you wrote at the end of the post, is not true.
It will not help to copy the array, because it only creates a reference to that array itself
Instead it is possible as follows

let myArray2 = [...myArr]
let last = myArr.pop()
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Peter Vivo • 
  const list = ['Apple', 'Orange', 3, 4, 'Football', 'Cricket'];
  list.slice(-1)?.[0]; // 'Cricket'
  'Cricket'.slice(-1)?.[0]; // 't'
  [].slice(-1)?.[0]; // undefined
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