Here is my JavaScript code so far:
var linkElement = document.getElementById("BackButton");
var loc_array = document.location.href.split('/');
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length-2])));
linkElement.appendChild(newT);
Currently it takes the second to last item in the array from the URL. However, I want to do a check for the last item in the array to be "index.html" and if so, grab the third to last item instead.
if (loc_array[loc_array.length - 1] === 'index.html') {
// do something
} else {
// something else
}
In the event that your server serves the same file for "index.html" and "inDEX.htML" you can also use: .toLowerCase().
Though, you might want to consider doing this server-side if possible: it will be cleaner and work for people without JS.
EDIT - ES-2022
Using ES-2022 Array.at(), the above may be written like this:
if (loc_array.at(-1) === 'index.html') {
// do something
} else {
// something else
}
x = string.split('/'); return x[x.length-1], you could do return x.split('/').pop() –
Phenazine .at as it was added by an entirely different user and is an entirely different approach than the one written by the original author. Here's a dedicated answer with the .at approach: https://mcmap.net/q/44989/-get-the-last-item-in-an-array –
Equiprobable Array.pop() because it is doing something else, just use .at(-1) –
Tigges at() has a possible undefined in typescript –
Hershel Not sure if there's a drawback, but this seems quite concise:
arr.slice(-1)[0]
or
arr.slice(-1).pop()
Both will return undefined if the array is empty.
const [lastItem] = arr.slice(-1) –
Generalization arr[arr.length-1] –
Agiotage Use Array.pop:
var lastItem = anArray.pop();
Important : This returns the last element and removes it from the array
filename.split('.').pop() –
Mckeever const lastItem = [...anArray].pop() would be a way to avoid the mutation –
Swing A shorter version of what @chaiguy posted:
Array.prototype.last = function() {
return this[this.length - 1];
}
Reading the -1 index returns undefined already.
EDIT:
These days the preference seems to be using modules and to avoid touching the prototype or using a global namespace.
export function last(array) {
return array[array.length - 1];
}
var lastItem = [3,2,1,5].last();. The value of lastItem is 5. –
Canning Do NOT modify objects you Do NOT own. It's dangerous because of many reasons, such as 1. Other developers working in your team could get confused as this method is not standard 2.with any update in libraries or even using a lower or higher ECMAScript version it could easily get LOST! –
Batory Array.prototype, but you should use Object.assign(Array.prototype, 'last', { value: function () { … } });. Otherwise the property will be enumerable. –
Schooling last is no standard in this case. –
Batory Array.prototype.last() can do: no matter the implementation, it'll return the last element, without removing it (because .pop() already exists for that), so in this case it's almost certainly perfectly fine, even if someone else also implements that same function. They'll overwrite each other and keep doing exactly the same thing. –
Considerate Object.assign() does not seem to work here, whereas regular assignment to the prototype object does. –
Grenadier Two options are:
var last = arr[arr.length - 1]
or
var last = arr.slice(-1)[0]
The former is faster, but the latter looks nicer
Today 2020.05.16 I perform tests of chosen solutions on Chrome v81.0, Safari v13.1 and Firefox v76.0 on MacOs High Sierra v10.13.6
arr[arr.length-1] (D) is recommended as fastest cross-browser solutionarr.pop() (A) and immutable _.last(arr) (L) are fast
I test two cases for solutions:
for two cases
function A(arr) {
return arr.pop();
}
function B(arr) {
return arr.splice(-1,1);
}
function C(arr) {
return arr.reverse()[0]
}
function D(arr) {
return arr[arr.length - 1];
}
function E(arr) {
return arr.slice(-1)[0] ;
}
function F(arr) {
let [last] = arr.slice(-1);
return last;
}
function G(arr) {
return arr.slice(-1).pop();
}
function H(arr) {
return [...arr].pop();
}
function I(arr) {
return arr.reduceRight(a => a);
}
function J(arr) {
return arr.find((e,i,a)=> a.length==i+1);
}
function K(arr) {
return $(arr).get(-1);
}
function L(arr) {
return _.last(arr);
}
function M(arr) {
return _.nth(arr, -1);
}
// ----------
// TEST
// ----------
let loc_array=["domain","a","b","c","d","e","f","g","h","file"];
log = (f)=> console.log(`${f.name}: ${f([...loc_array])}`);
[A,B,C,D,E,F,G,H,I,J,K,L,M].forEach(f=> log(f));<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js" integrity="sha256-VeNaFBVDhoX3H+gJ37DpT/nTuZTdjYro9yBruHjVmoQ=" crossorigin="anonymous"></script>Example results for Chrome for short string
Getting the last item in an array is possible via the length property. Since the array count starts at 0, you can pick the last item by referencing the array.length - 1 item
const arr = [1,2,3,4];
const last = arr[arr.length - 1];
console.log(last); // 4Another option is using the new Array.prototype.at() method which takes an integer value and returns the item at that index. Negative integers count back from the last item in the array so if we want the last item we can just pass in -1
const arr = [1,2,3,4];
const last = arr.at(-1);
console.log(last); // 4Another option is using the new findLast method. You can see the proposal here (currently in stage 4)
const arr = [1,2,3,4];
const last = arr.findLast(x => true);
console.log(last); // 4Another option is using the Array.prototype.slice() method which returns a shallow copy of a portion of an array into a new array object.
const arr = [1,2,3,4];
const last = arr.slice(-1)[0];
console.log(last); // 4arr.findLast(() => true); since your version would not "find" falsy values like 0 or "", ... –
Arnelle Here's how to get it with no effect on the original ARRAY
a = [1,2,5,6,1,874,98,"abc"];
a.length; //returns 8 elements
If you use pop(), it will modify your array
a.pop(); // will return "abc" AND REMOVES IT from the array
a.length; // returns 7
But you can use this so it has no effect on the original array:
a.slice(-1).pop(); // will return "abc" won't do modify the array
// because slice creates a new array object
a.length; // returns 8; no modification and you've got you last element
pop() then: just do arr.slice(-1)[0] –
Noto The "cleanest" ES6 way (IMO) would be:
const foo = [1,2,3,4];
const bar = [...foo].pop();
This avoids mutating foo, as .pop() would had, if we didn't used the spread operator.
That said, I like aswell the foo.slice(-1)[0] solution.
.slice(-1)[0] but it's slower. Might as well use .slice –
Tweeter Previously you can use
x[x.length - 1]Update: Since the most recent updates we can use the below method.
const y = x.at(-1)
arr[arr.length - 1] as it is both more readable and nearly an order of magnitude faster on most browsers. –
Scheel const [lastItem] = array.slice(-1);Array.prototype.slice with -1 can be used to create a new Array containing only the last item of the original Array, you can then use Destructuring Assignment to create a variable using the first item of that new Array.
const lotteryNumbers = [12, 16, 4, 33, 41, 22];
const [lastNumber] = lotteryNumbers.slice(-1);
console.log(lotteryNumbers.slice(-1));
// => [22]
console.log(lastNumber);
// => 22.slice(-1) answer was already given multiple times, starting in 2012, and its implications were discussion in detail (unlike here). Please do not give repetitive answers just to get some upvotes. –
Gilus const [secondLast, last] = lotteryNumbers.slice(-2) –
Ismaelisman You can use relative indexing with Array#at:
const myArray = [1, 2, 3]
console.log(myArray.at(-1))
// => 3
jscOptions=--useAtMethod=true). The lastItem proposal will probably be withdrawn. –
Cannady I'd rather use array.pop() than indexes.
while(loc_array.pop()!= "index.html"){
}
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length])));
this way you always get the element previous to index.html (providing your array has isolated index.html as one item). Note: You'll lose the last elements from the array, though.
const lastElement = myArray[myArray.length - 1];
This is the best options from performance point of view (~1000 times faster than arr.slice(-1)).
You can use this pattern...
let [last] = arr.slice(-1);
While it reads rather nicely, keep in mind it creates a new array so it's less efficient than other solutions but it'll almost never be the performance bottleneck of your application.
If one wants to get the last element in one go, he/she may use Array#splice():
lastElement = document.location.href.split('/').splice(-1,1);
Here, there is no need to store the split elements in an array, and then get to the last element. If getting last element is the only objective, this should be used.
Note: This changes the original array by removing its last element. Think of splice(-1,1) as a pop() function that pops the last element.
["hi"] vs "hi". –
Agiotage Getting the last item of an array can be achieved by using the slice method with negative values.
You can read more about it here at the bottom.
var fileName = loc_array.slice(-1)[0];
if(fileName.toLowerCase() == "index.html")
{
//your code...
}
Using pop() will change your array, which is not always a good idea.
arr.slice(-1)[0], like this answer. –
Newman array[array.length - 1] jsperf.com/get-last-item-from-array/13 –
Pontifex Multiple ways to find last value of an array in javascript
var arr = [1,2,3,4,5];
console.log(arr.slice(-1)[0])
console.log(arr[arr.length-1])
const [last] = [...arr].reverse();
console.log(last)
let copyArr = [...arr];
console.log(copyArr.reverse()[0]);var arr = [1,2,3,4,5];
console.log(arr.pop())
arr.push(5)
console.log(...arr.splice(-1));let arr = [1, 2, 3, 4, 5];
Object.defineProperty(arr, 'last',
{ get: function(){
return this[this.length-1];
}
})
console.log(arr.last);console.log(arr.reverse()[0]) - congratulations, you just modified the original array. –
Grube This question has been around a long time, so I'm surprised that no one mentioned just putting the last element back on after a pop().
arr.pop() is exactly as efficient as arr[arr.length-1], and both are the same speed as arr.push().
Therefore, you can get away with:
---EDITED [check that thePop isn't undefined before pushing]---
let thePop = arr.pop()
thePop && arr.push(thePop)
---END EDIT---
Which can be reduced to this (same speed [EDIT: but unsafe!]):
arr.push(thePop = arr.pop()) //Unsafe if arr empty
This is twice as slow as arr[arr.length-1], but you don't have to stuff around with an index. That's worth gold on any day.
Of the solutions I've tried, and in multiples of the Execution Time Unit (ETU) of arr[arr.length-1]:
arr[arr.length - 1] ------> 1 -----> 1
let myPop = arr.pop()
arr.push(myPop) ------> 2 -----> 2
arr.slice(-1).pop() ------> 36 -----> 924
arr.slice(-1)[0] ------> 36 -----> 924
[...arr].pop() ------> 120 -----> ~21,000,000 :)
The last three options, ESPECIALLY [...arr].pop(), get VERY much worse as the size of the array increases. On a machine without the memory limitations of my machine, [...arr].pop() probably maintains something like it's 120:1 ratio. Still, no one likes a resource hog.
[] will be turned into [undefined]. You need to protect backward push with explicit undefined check, something like myPop !== undefined && arr.push(myPop) –
Parkman Just putting another option here.
loc_array.splice(-1)[0] === 'index.html'
I found the above approach more clean and short onliner. Please, free feel to try this one.
Note: It will modify the original array, if you don't want to modify it you can use slice()
loc_array.slice(-1)[0] === 'index.html'
Thanks @VinayPai for pointing this out.
.slice(-1) answer was already given multiple times, starting in 2012, and its implications were discussion in detail (unlike here). Please do not give repetitive answers just to get some upvotes. –
Gilus In the spirit of another answer that used reduceRight(), but shorter:
[3, 2, 1, 5].reduceRight(a => a);
It relies on the fact that, in case you don't provide an initial value, the very last element is selected as the initial one (check the docs here). Since the callback just keeps returning the initial value, the last element will be the one being returned in the end.
Beware that this should be considered Javascript art and is by no means the way I would recommend doing it, mostly because it runs in O(n) time, but also because it hurts readability.
The best way I see (considering you want it more concise than array[array.length - 1]) is this:
const last = a => a[a.length - 1];
Then just use the function:
last([3, 2, 1, 5])
The function is actually useful in case you're dealing with an anonymous array like [3, 2, 1, 5] used above, otherwise you'd have to instantiate it twice, which would be inefficient and ugly:
[3, 2, 1, 5][[3, 2, 1, 5].length - 1]
Ugh.
For instance, here's a situation where you have an anonymous array and you'd have to define a variable, but you can use last() instead:
last("1.2.3".split("."));
ES6 object destructuring is another way to go.
const {length, [length-1]: last}=[1,2,3,4,5]
console.log(last)You extract length property from Array using object destructuring. You create another dynamic key using already extracted key by [length-1] and assign it to last, all in one line.
length is the first index of the array. but [length-1] is the last index (the one before it). :last is the alias used to define the last index (or the one before the first one to be exact) –
Uncouple length then use computed property name [length -1] to get the last element. –
Mut For those not afraid to overload the Array prototype (and with enumeration masking you shouldn't be):
Object.defineProperty( Array.prototype, "getLast", {
enumerable: false,
configurable: false,
writable: false,
value: function() {
return this[ this.length - 1 ];
}
} );
I generally use underscorejs, with it you can just do
if (_.last(loc_array) === 'index.html'){
etc...
}
For me that is more semantic than loc_array.slice(-1)[0]
jQuery solves this neatly:
> $([1,2,3]).get(-1)
3
> $([]).get(-1)
undefined
With ECMA 2022 you have a new property at(). To get the last element from a Array or a string you can use at with the negative index -1. [1,2,3].at(-1). https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/at
If you like more fluent like arr.last to receive the last item you can define your own property to the array object.
if (!Array.prototype.hasOwnProperty("last")) {
Object.defineProperty(Array.prototype, "last", {
get() {
return this.at(-1);
}
});
}
a = [1,2,3];
console.log(a.last);To prevent removing last item from origin array you could use
Array.from(myArray).pop()
Mostly supported of all browsers (ES6)
In ECMAScript proposal Stage 1 there is a suggestion to add an array property that will return the last element: proposal-array-last.
Syntax:
arr.lastItem // get last item
arr.lastItem = 'value' // set last item
arr.lastIndex // get last index
You can use polyfill.
Proposal author: Keith Cirkel(chai autor)
reverse() !!!A few answers mention reverse but don't mention the fact that reverse modifies the original array, and doesn't (as in some other language or frameworks) return a copy.
var animals = ['dog', 'cat'];
animals.reverse()[0]
"cat"
animals.reverse()[0]
"dog"
animals.reverse()[1]
"dog"
animals.reverse()[1]
"cat"
This can be the worst type of code to debug!
[...animals].reverse() –
Stroh [1,3,4,5,"last"].slice().reverse()[0] –
Hildegaard I think this should work fine.
var arr = [1, 2, 3];
var last_element = arr.reverse()[0];
Just reverse the array and get the first element.
Edit: As mentioned below, the original array will be reversed. To avoid that you can change the code to:
var arr = [1, 2, 3];
var last_element = arr.slice().reverse()[0];
This will create a copy of the original array.
arr.slice().pop() –
Cattleya Personally I would upvote answer by kuporific / kritzikratzi. The array[array.length-1] method gets very ugly if you're working with nested arrays.
var array = [[1,2,3], [4,5,6], [7,8,9]]
array.slice(-1)[0]
//instead of
array[array.length-1]
//Much easier to read with nested arrays
array.slice(-1)[0].slice(-1)[0]
//instead of
array[array.length-1][array[array.length-1].length-1]
You can add a last() function to the Array prototype.
Array.prototype.last = function () {
return this[this.length - 1];
};
EDIT:
You can use a Symbol to avoid incompatibility with other code:
const last = Symbol('last');
Array.prototype[last] = function() {
return this[this.length - 1];
};
console.log([0, 1][last]());As per ES2022, You can use Array.at() method which takes an integer value and returns the item at that index. Allowing for positive and negative integers. Negative integers count back from the last item in the array.
Demo :
const href = 'www.abc.com/main/index.html';
const loc_array = href.split('/');
// To access elements from an array we can use Array.at()
console.log(loc_array.at(-1)); // This will return item at last index.You could add a new property getter to the prototype of Array so that it is accessible through all instances of Array.
Getters allow you to access the return value of a function just as if it were the value of a property. The return value of the function of course is the last value of the array (this[this.length - 1]).
Finally you wrap it in a condition that checks whether the last-property is still undefined (not defined by another script that might rely on it).
Object.defineProperty(Array.prototype, 'last', {
get : function() {
return this[this.length - 1];
}
});
// Now you can access it like
[1, 2, 3].last; // => 3
// or
var test = [50, 1000];
alert(test.last); // Says '1000'
Array.prototype.last is always undefined? The if isn't working under Chrome 36 –
Hegumen EDITED:
Recently I came up with one more solution which I now think is the best for my needs:
function w(anArray) {
return {
last() {
return anArray [anArray.length - 1];
};
};
}
With the above definition in effect I can now say:
let last = w ([1,2,3]).last();
console.log(last) ; // -> 3
The name "w" stands for "wrapper". You can see how you could easily add more methods besides 'last()' to this wrapper.
I say "best for my needs", because this allows me to easily add other such "helper methods" to any JavaScript built-in type. What comes to mind are the car() and cdr() of Lisp for instance.
w function just make the function return the last item. –
Tweeter w([1,2,3]).length is undefined. w([1,2,3])[1] is undefined. Does not seem like a wrapper to me. And there is a syntax error. You have an extra ';'. See https://mcmap.net/q/45725/-trim-specific-character-from-a-string for how to write a class wrapper (SutString class) and use reflection to populate that wrapper. Though, imho, wrappers are overkill. Better to use encapsulation, like you almost have. return { arr: anArray, last() { return anArray[anArray.length - 1]; } };. Also, w is way too generic. Call is ArrayW or something. –
Starstudded I think the easiest to understand for beginners and super inefficient way is: 😆
var array = ['fenerbahce','arsenal','milan'];
var reversed_array = array.reverse(); //inverts array [milan,arsenal,fenerbahce]
console.log(reversed_array[0]) // result is "milan".
If you're using JS, I would suggest checking out Ramda which is a functional-programming library (like Lodash and Underscore, except more advanced and modular). Ramda provides this with R.last
import * as R from 'ramda';
R.last(['fi', 'fo', 'fum']); //=> 'fum'
R.last([]); //=> undefined
R.last('abc'); //=> 'c'
R.last(''); //=> ''
It further provides init, head, tail. List monster from (Learn You a Haskell)
R.pipe(R.take(1), x=>x*2) (also works with typescript) –
Jeffers const m = x => y => x * y; R.pipe(R.take(1), m(2), m(3), m(4)) What's the point here? I mean I'm down for helping you to learn Ramda but this has 0 to do with my answer? And it seems like you're a little bitter that you're struggling to grok Ramda so you downvoted me (not a good way to start a conversation). Keep on learning though. Btw, you can also do x = R.pipe( R.take(1), y=>y*2 ); y = R.pipe( x, z => z*2 ) –
Jeffers pipe and that you only need to import what you're using. In addition anything imported that you're not using is subject to "tree shaking" which Webpack can actually remove in a bundle (dead code goes away). This makes it the Ramba method more-pure (functionally), more concise (look at my example), faster (no wrapping of objects), and smaller (no need to import a class, or all of the operators, and you can remove operators you don't use automagically) –
Jeffers a.keys(), you do Object.keys(a)? Why? Because likely somewhere someone extended Object.prototype to already have keys and es didn't want to break backwards compat. This isn't a problem though with the Ramda method. R.pipe(R.keys, R.join(''))( {foo:1,bar:2} ); You just compose functions together. –
Jeffers I'll suggest to create helper function and reuse it every time, you'll need it. Lets make function more general to be able to get not only last item, but also second from the last and so on.
function last(arr, i) {
var i = i || 0;
return arr[arr.length - (1 + i)];
}
Usage is simple
var arr = [1,2,3,4,5];
last(arr); //5
last(arr, 1); //4
last(arr, 9); //undefined
Now, lets solve the original issue
Grab second to last item form array. If the last item in the loc_array is "index.html" grab the third to last item instead.
Next line does the job
last(loc_array, last(loc_array) === 'index.html' ? 2 : 1);
So, you'll need to rewrite
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length-2])));
in this way
var newT = document.createTextNode(unescape(capWords(last(loc_array, last(loc_array) === 'index.html' ? 2 : 1))));
or use additional variable to increase readability
var nodeName = last(loc_array, last(loc_array) === 'index.html' ? 2 : 1);
var newT = document.createTextNode(unescape(capWords(nodeName)));
Normally you are not supposed to mess with the prototype of built-in types but here is a hack/shortcut:
Object.defineProperty(Array.prototype, 'last', {
get() {
return this[this.length - 1];
}
});
This will allow all array objects to have a last property, which you can use like so:
const letters = ['a', 'b', 'c', 'd', 'e'];
console.log(letters.last); // 'e'
You are not supposed to mess with a built-in type's prototype because you never when a new ES version will be released and in the event that a new version uses the same property name as your custom property, all sorts of breaks can happen. Also, it makes it hard for others to follow your code, especially for people joining the team. You COULD make the property to something that you know an ES version would never use, like listLastItem but that is at the discretion of the developer.
Or you can use a simple method:
const getLast = (list) => list[list.length - 1];
const last = getLast([1,2,3]); // returns 3
Proposal for Array.prototype.findLast is now on Stage 3!
Here's how you can use it:
const array = [1, 2, 3, 4, 5];
const last_element = array.findLast((item) => true);
console.log(last_element);You can read more in this V8 blog post.
You can find more in "New in Chrome" series.
Using ES6/ES2015 spread operator (...) you can do the following way.
const data = [1, 2, 3, 4]
const [last] = [...data].reverse()
console.log(last)Please notice that using spread operator and reverse we did not mutated original array, this is a pure way of getting a last element of the array.
Using lodash _.last(array) Gets the last element of array.
data = [1,2,3]
last = _.last(data)
console.log(last)<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>How about something like below:
if ('index.html' === array[array.length - 1]) {
//do this
} else {
//do that
}
If using Underscore or Lodash, you can use _.last(), so something like:
if ('index.html' === _.last(array)) {
//do this
} else {
//do that
}
Or you can create your own last function:
const _last = arr => arr[arr.length - 1];
and use it like:
if ('index.html' === _last(array)) {
//do this
} else {
//do that
}
Will this work?
if (loc_array.pop() == "index.html"){
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length-3])));
}
else{
var newT = document.createTextNode(unescape(capWords(loc_array[loc_array.length-2])));
}
.pop() returns the last element and also removes it, so your indexes change. –
Goggin arr.slice().pop() - this creates a new array –
Romona This method will not mess with your prototype. It also guards against 0 length arrays, along with null/undefined arrays. You can even override the default value if the returned default value might match an item in your array.
const items = [1,2,3]
const noItems = []
/**
* Returns the last item in an array.
* If the array is null, undefined, or empty, the default value is returned.
*/
function arrayLast (arrayOrNull, defVal = undefined) {
if (!arrayOrNull || arrayOrNull.length === 0) {
return defVal
}
return arrayOrNull[arrayOrNull.length - 1]
}
console.log(arrayLast(items))
console.log(arrayLast(noItems))
console.log(arrayLast(null))
console.log(arrayLast(items, 'someDefault'))
console.log(arrayLast(noItems, 'someDefault'))
console.log(arrayLast(null, 'someDefault'))You can achieve this issue also without extracting an array from the url
This is my alternative
var hasIndex = (document.location.href.search('index.html') === -1) ? doSomething() : doSomethingElse();
!Greetings¡
This is clean and efficient:
let list = [ 'a', 'b', 'c' ]
(xs => xs[xs.length - 1])(list)
If you install a pipe operator using Babel it becomes:
list |> (xs => xs[xs.length - 1])
Another ES6 only option would be to use Array.find(item, index)=> {...}) as follows:
const arr = [1, 2, 3];
const last = arr.find((item, index) => index === arr.length - 1);
little practical value, posted to show that index is also available for your filtering logic.
Array.prototype.last = function(){
return this[this.length - 1];
}
let a = [1, 2, 3, [4, 5]];
console.log(a.last());
// [ 4, 5 ]
console.log(a.last().last());
// 5
Array.prototype.last = function(val=null) {
if (this.length === 0) {
if (val) this[0] = val;
else return null;
}
temp = this;
while(typeof temp[temp.length-1] === "object") {
temp = temp[temp.length-1];
}
if (val) temp[temp.length-1] = val; //Setter
else return temp[temp.length-1]; //Getter
}
var arr = [[1, 2], [2, 3], [['a', 'b'], ['c', 'd']]];
console.log(arr.last()); // 'd'
arr.last("dd");
console.log(arr); // [ [ 1, 2 ], [ 2, 3 ], [ [ 'a', 'b' ], [ 'c', 'dd' ] ] ]
The arrow function makes the fastest-performing method more concise, by not repeating the name of the array.
var lastItem = (a => a[a.length - 1])(loc_array);
var lastItem = a[a.length-1] –
Gorga a within the context of the function. It's like doing var getLast = a => a[a.length - 1]; var lastItem = getLast(loc_array), but the "getLast" function is in-lined, not separately defined. –
Matronage var str = ["stackoverflow", "starlink"];
var last = str[str.length-1];//basically you are putting the last index value into the array and storing it in la
There is also a npm module, that add last to Array.prototype
npm install array-prototype-last --save
usage
require('array-prototype-last');
[1, 2, 3].last; //=> 3
[].last; //=> undefined
Array.prototype.last = function(){ return this[this.length - 1]; } + Object.defineProperty(Array.prototype, 'last', {enumerable: false}); –
Electrostatics () in code, but this "property" stay in fact a function called each time, right? –
Electrostatics For a readable and concise solution, you can use a combination of Array.prototype.slice and destructuring.
const linkElement = document.getElementById("BackButton");
const loc_array = document.location.href.split('/');
// assign the last three items of the array to separate variables
const [thirdLast, secondLast, last] = loc_array.slice(-3);
// use the second last item as the slug...
let parentSlug = secondLast;
if (last === 'index.html') {
// ...unless this is an index
parentSlug = thirdLast;
}
const newT = document.createTextNode(
unescape(
capWords(parentSlug)
)
);
linkElement.appendChild(newT);
But to simply get the last item in an array, I prefer this notation:
const [lastItem] = loc_array.slice(-1);
The
findLastIndex()method iterates the array in reverse order and returns the index of the first element that satisfies the provided testing function. If no elements satisfy the testing function, -1 is returned.
const arr = [1,2,3,4];
const lastIndex = arr.findLastIndex(x => true);
console.log(arr[lastIndex]); // 4PS: findLastIndex() method is supported by all browsers and on Node.js version 18+.
see browser compatibility
arr.at(-1) (added in ES2022). See https://mcmap.net/q/44989/-get-the-last-item-in-an-array –
Megargee Using reduceRight:
[3,2,1,5].reduceRight((a,v) => a ? a : v);
return and curly braces. –
Pentangular simple answer
const array = [1,2,3]
array[array.length - 1]
The pop() and slice() both method are faster. You can use pop() method if you are fine with modifying the array. If you don't want to change the array, the slice() method can be used.
let arrItems = [12, 24, 60, 80, 10, 14, 123];
console.time('using array length');
let lastItem = arrItems[arrItems.length - 1];
console.log(lastItem);
console.timeEnd('using array length');
console.time('using slice method');
let lastItem1 = arrItems.slice(-1)[0];
console.log(lastItem1);
console.timeEnd('using slice method');
console.time('using pop method');
let lastItem2 = arrItems.pop();
console.log(lastItem2);
console.timeEnd('using pop method');
//Output:
//123
//using array length: 0.200ms
//123
//using slice method: 0.175ms
//123
//using pop method: 0.012msIn case your indices are random strings, уоu can use this:
arr[Object.keys(arr)[Object.keys(arr).length - 1]]
You can use snippet that extends the functionality of arrays by adding a new method called last(). This method can be used various approach to retrieve the last item of an array. Choose one of the many possibilities:
Array.prototype.last = function() {
return this[this.length - 1]
// return this.slice(-1)[0]
// return this.at(-1)
// return this.findLast(x => true)
// return [...this].reverse()[0]
// return this.reduceRight(_ => _)
// return this.slice().reverse()[0]
// return this.pop()
// return this.splice(-1,1)[0]
// return [...this].pop()
// return this.find((_,i,a)=>a.length==i+1)
}
console.log([2,4,6].last()) // 6
console.log([1, 2, 3].last()) // 3The simple way to get last item of array:
var last_item = loc_array.reverse()[0];
Of course, we need to check to make sure array has at least one item first.
reverse changes the original array so if you run this twice in a row you get different results (asusming length > 1) –
Khano to access the last element in array using c# we can use GetUpperBound(0)
(0) in case if this one dimention array
my_array[my_array.GetUpperBound(0)] //this is the last element in this one dim array
array.reverse()[0]
That's so simple
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