Bdtjtk

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.

Use Array.pop:

var lastItem = anArray.pop();

Important : This returns the last element and removes it from the array

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];

}

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

http://jsperf.com/slice-vs-length-1-arr

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 

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.

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.

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.

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.

jQuery solves this neatly:

> $([1,2,3]).get(-1)

3

> $().get(-1)

undefined

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 think if you only want get the element without remove, is more simple use this:

arr.slice(-1)

by the way... i didnt check performance, but i think is more simple and clean to write

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]

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:

let thePop = arr.pop()

arr.push(thePop)

Which can be reduced to this (same speed):

arr.push(thePop = arr.pop())

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]:

[Method]..............[ETUs 5 elems]...[ETU 1 million elems]

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.

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];

};

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).

if(typeof Array.prototype.last === 'undefined') {

    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'

Does not work in IE ≤ 8.

const lastElement = myArray[myArray.length - 1];

This is the best options from performance point of view (~1000 times faster than arr.slice(-1)).

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.

I think the easiest 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".

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)));

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)

The 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.

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>

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 can be done with lodash _.last or _.nth:

var data = [1, 2, 3, 4]

var last = _.nth(data, -1)

console.log(last)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

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.

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