Как найти последнее значение в массиве

Как найти последнее значение в массиве

The many answers in this thread present us with many different options. To be able to choose from them I needed to understand their behavior and performance. In this answer I will share my findings with you, benchmarked against PHP versions 5.6.38, 7.2.10 and 7.3.0RC1 (expected Dec 13 2018).

The options (<<option code>>s) I will test are:

  • option .1. $x = array_values(array_slice($array, -1))[0]; (as suggested by rolacja)
  • option .2. $x = array_slice($array, -1)[0]; (as suggested by Stoutie)
  • option .3. $x = array_pop((array_slice($array, -1))); (as suggested by rolacja)
  • option .4. $x = array_pop((array_slice($array, -1, 1))); (as suggested by Westy92)
  • option .5. $x = end($array); reset($array); (as suggested by Iznogood)
  • option .6. $x = end((array_values($array))); (as suggested by TecBrat)
  • option .7. $x = $array[count($array)-1]; (as suggested by Mirko Pagliai)
  • option .8. $keys = array_keys($array); $x = $array[$keys[count($keys)-1]]; (as suggested by thrau)
  • option .9. $x = $array[] = array_pop($array); (as suggested by user2782001)
  • option 10. $x = $array[array_key_last($array)]; (as suggested by Quasimodo’s clone ; available per PHP 7.3)

(functions mentioned: array_key_last , array_keys , array_pop , array_slice , array_values , count , end , reset)

The test inputs (<<input code>>s) to combine with:

  • null = $array = null;
  • empty = $array = [];
  • last_null = $array = ["a","b","c",null];
  • auto_idx = $array = ["a","b","c","d"];
  • shuffle = $array = []; $array[1] = "a"; $array[2] = "b"; $array[0] = "c";
  • 100 = $array = []; for($i=0;$i<100;$i++) { $array[] = $i; }
  • 100000 = $array = []; for($i=0;$i<100000;$i++) { $array[] = $i; }

For testing I will use the 5.6.38, 7.2.10 and 7.3.0RC1 PHP docker containers like:

sudo docker run -it --rm php:5.6.38-cli-stretch php -r '<<<CODE HERE>>>'

Each combination of the above listed <<option code>>s and <<input code>>s will be run on all versions of PHP. For each test run the following code snippet is used:

<<input code>>  error_reporting(E_ALL);  <<option code>>  error_reporting(0); $before=microtime(TRUE); for($i=0;$i<100;$i++){echo ".";for($j=0;$j<100;$j++){  <<option code>>  }}; $after=microtime(TRUE); echo "n"; var_dump($x); echo round(($after-$before)/(100*100)*1000*1000*1000);

For each run this will var_dump the last retrieved last value of the test input and print the average duration of one iteration in femtoseconds (0.000000000000001th of a second).

The results are as follows:

/==========================================================================================================================================================================================================================================================================================================================================================================================================================
||                                                                      ||                            T  E  S  T     I  N  P  U  T     -     5  .  6  .  3  8                            ||                             T  E  S  T     I  N  P  U  T     -     7  .  2  .  1  0                           ||                             T  E  S  T     I  N  P  U  T     -     7  .  3  .  0  R  C  1                     ||
||                                                                      ||          null |         empty |     last_null |      auto_idx |       shuffle |           100 |        100000 ||          null |         empty |     last_null |      auto_idx |       shuffle |           100 |        100000 ||          null |         empty |     last_null |      auto_idx |       shuffle |           100 |        100000 ||
||============================OPTIONS - ERRORS==========================++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============<|
||  1.  $x = array_values(array_slice($array, -1))[0];                  ||       W1 + W2 |            N1 |             - |             - |             - |             - |             - ||       W1 + W2 |            N1 |             - |             - |             - |             - |             - ||       W1 + W2 |            N1 |             - |             - |             - |             - |             - ||
||  2.  $x = array_slice($array, -1)[0];                                ||            W1 |            N1 |             - |             - |             - |             - |             - ||            W1 |            N1 |             - |             - |             - |             - |             - ||            W1 |            N1 |             - |             - |             - |             - |             - ||
||  3.  $x = array_pop((array_slice($array, -1)));                      ||       W1 + W3 |             - |             - |             - |             - |             - |             - ||  W1 + N2 + W3 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||  W1 + N2 + W3 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||
||  4.  $x = array_pop((array_slice($array, -1, 1)));                   ||       W1 + W3 |             - |             - |             - |             - |             - |             - ||  W1 + N2 + W3 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||  W1 + N2 + W3 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||
||  5.  $x = end($array); reset($array);                                ||       W4 + W5 |             - |             - |             - |             - |             - |             - ||       W4 + W5 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||       W4 + W5 |             - |             - |             - |             - |             - |             - ||
||  6.  $x = end((array_values($array)));                               ||       W2 + W4 |             - |             - |             - |             - |             - |             - ||  W2 + N2 + W4 |             - |             - |             - |             - |             - |             - ||  W2 + N2 + W4 |            N2 |            N2 |            N2 |            N2 |            N2 |            N2 ||
||  7.  $x = $array[count($array)-1];                                   ||             - |            N3 |             - |             - |             - |             - |             - ||            W7 |            N3 |             - |             - |             - |             - |             - ||            W7 |            N3 |             - |             - |             - |             - |             - ||
||  8.  $keys = array_keys($array); $x = $array[$keys[count($keys)-1]]; ||            W6 |       N3 + N4 |             - |             - |             - |             - |             - ||       W6 + W7 |       N3 + N4 |             - |             - |             - |             - |             - ||       W6 + W7 |       N3 + N4 |             - |             - |             - |             - |             - ||
||  9.  $x = $array[] = array_pop($array);                              ||            W3 |             - |             - |             - |             - |             - |             - ||            W3 |             - |             - |             - |             - |             - |             - ||            W3 |             - |             - |             - |             - |             - |             - ||
|| 10.  $x = $array[array_key_last($array)];                            ||            F1 |            F1 |            F1 |            F1 |            F1 |            F1 |            F1 ||            F2 |            F2 |            F2 |            F2 |            F2 |            F2 |            F2 ||            W8 |            N4 |            F2 |            F2 |            F2 |            F2 |            F2 ||
||========================OPTIONS - VALUE RETRIEVED=====================++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============<|
||  1.  $x = array_values(array_slice($array, -1))[0];                  ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  2.  $x = array_slice($array, -1)[0];                                ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  3.  $x = array_pop((array_slice($array, -1)));                      ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  4.  $x = array_pop((array_slice($array, -1, 1)));                   ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  5.  $x = end($array); reset($array);                                ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  6.  $x = end((array_values($array)));                               ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |   bool(false) |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  7.  $x = $array[count($array)-1];                                   ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "b" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "b" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "b" |       int(99) |    int(99999) ||
||  8.  $keys = array_keys($array); $x = $array[$keys[count($keys)-1]]; ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
||  9.  $x = $array[] = array_pop($array);                              ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||          NULL |          NULL |          NULL | string(1) "d" | string(1) "c" |       int(99) |    int(99999) ||
|| 10.  $x = $array[array_key_last($array)];                            ||           N/A |           N/A |           N/A |           N/A |           N/A |           N/A |           N/A ||           N/A |           N/A |           N/A |           N/A |           N/A |           N/A |           N/A ||           N/A |           N/A |           N/A |           N/A |           N/A |           N/A |           N/A ||
||=================OPTIONS - FEMTOSECONDS PER ITERATION=================++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============++===============+===============+===============+===============+===============+===============+===============<|
||  1.  $x = array_values(array_slice($array, -1))[0];                  ||           803 |           466 |           390 |           384 |           373 |           764 |     1.046.642 ||           691 |           252 |           101 |           128 |            93 |           170 |        89.028 ||           695 |           235 |            90 |            97 |            95 |           188 |        87.991 ||
||  2.  $x = array_slice($array, -1)[0];                                ||           414 |           349 |           252 |           248 |           246 |           604 |     1.038.074 ||           373 |           249 |            85 |            91 |            90 |           164 |        90.750 ||           367 |           224 |            78 |            85 |            80 |           155 |        86.141 ||
||  3.  $x = array_pop((array_slice($array, -1)));                      ||           724 |           228 |           323 |           318 |           350 |           673 |     1.042.263 ||           988 |           285 |           309 |           317 |           331 |           401 |        88.363 ||           877 |           266 |           298 |           300 |           326 |           403 |        87.279 ||
||  4.  $x = array_pop((array_slice($array, -1, 1)));                   ||           734 |           266 |           358 |           356 |           349 |           699 |     1.050.101 ||           887 |           288 |           316 |           322 |           314 |           408 |        88.402 ||           935 |           268 |           335 |           315 |           313 |           403 |        86.445 ||
||  5.  $x = end($array); reset($array);                                ||           715 |           186 |           185 |           180 |           176 |           185 |           172 ||           674 |            73 |            69 |            70 |            66 |            65 |            70 ||           693 |            65 |            85 |            74 |            68 |            70 |            69 ||
||  6.  $x = end((array_values($array)));                               ||           877 |           205 |           320 |           337 |           304 |         2.901 |     7.921.860 ||           948 |           300 |           336 |           308 |           309 |           509 |    29.696.951 ||           946 |           262 |           301 |           309 |           302 |           499 |    29.234.928 ||
||  7.  $x = $array[count($array)-1];                                   ||           123 |           300 |           137 |           139 |           143 |           140 |           144 ||           312 |           218 |            48 |            53 |            45 |            47 |            51 ||           296 |           217 |            46 |            44 |            53 |            53 |            55 ||
||  8.  $keys = array_keys($array); $x = $array[$keys[count($keys)-1]]; ||           494 |           593 |           418 |           435 |           399 |         3.873 |    12.199.450 ||           665 |           407 |           103 |           109 |           114 |           431 |    30.053.730 ||           647 |           445 |            91 |            95 |            96 |           419 |    30.718.586 ||
||  9.  $x = $array[] = array_pop($array);                              ||           186 |           178 |           175 |           188 |           180 |           181 |           186 ||            83 |            78 |            75 |            71 |            74 |            69 |            83 ||            71 |            64 |            70 |            64 |            68 |            69 |            81 ||
|| 10.  $x = $array[array_key_last($array)];                            ||           N/A |           N/A |           N/A |           N/A |           N/A |           N/A |           N/A ||           N/A |           N/A |           N/A |           N/A |           N/A |           N/A |           N/A ||           370 |           223 |            49 |            52 |            61 |            57 |            52 ||
 =========================================================================================================================================================================================================================================================================================================================================================================================================================/

The above mentioned Fatal, Warning and Notice codes translate as:

F1 = Fatal error: Call to undefined function array_key_last() in Command line code on line 1
F2 = Fatal error: Uncaught Error: Call to undefined function array_key_last() in Command line code:1
W1 = Warning: array_slice() expects parameter 1 to be array, null given in Command line code on line 1
W2 = Warning: array_values() expects parameter 1 to be array, null given in Command line code on line 1
W3 = Warning: array_pop() expects parameter 1 to be array, null given in Command line code on line 1
W4 = Warning: end() expects parameter 1 to be array, null given in Command line code on line 1
W5 = Warning: reset() expects parameter 1 to be array, null given in Command line code on line 1
W6 = Warning: array_keys() expects parameter 1 to be array, null given in Command line code on line 1
W7 = Warning: count(): Parameter must be an array or an object that implements Countable in Command line code on line 1
W8 = Warning: array_key_last() expects parameter 1 to be array, null given in Command line code on line 1
N1 = Notice: Undefined offset: 0 in Command line code on line 1
N2 = Notice: Only variables should be passed by reference in Command line code on line 1
N3 = Notice: Undefined offset: -1 in Command line code on line 1
N4 = Notice: Undefined index:  in Command line code on line 1

Based on this output I draw the following conclusions:

  • newer versions of PHP perform better with the exception of these options that became significantly slower:
    • option .6. $x = end((array_values($array)));
    • option .8. $keys = array_keys($array); $x = $array[$keys[count($keys)-1]];
  • these options scale best for very large arrays:
    • option .5. $x = end($array); reset($array);
    • option .7. $x = $array[count($array)-1];
    • option .9. $x = $array[] = array_pop($array);
    • option 10. $x = $array[array_key_last($array)]; (since PHP 7.3)
  • these options should only be used for auto-indexed arrays:
    • option .7. $x = $array[count($array)-1]; (due to use of count)
    • option .9. $x = $array[] = array_pop($array); (due to assigning value losing original key)
  • this option does not preserve the array’s internal pointer
    • option .5. $x = end($array); reset($array);
  • this option is an attempt to modify option .5. to preserve the array’s internal pointer (but sadly it does not scale well for very large arrays)
    • option .6. $x = end((array_values($array)));
  • the new array_key_last function seems to have none of the above mentioned limitations with the exception of still being an RC at the time of this writing (so use the RC or await it’s release Dec 2018):
    • option 10. $x = $array[array_key_last($array)]; (since PHP 7.3)

A bit depending on whether using the array as stack or as queue you can make variations on option 9.

Источник

(PHP 4, PHP 5, PHP 7, PHP 8)

array_pop — Извлекает последний элемент массива

Описание

array_pop(array &$array): mixed

Замечание: Эта функция при вызове
сбрасывает указатель массива, переданного параметром.

Список параметров

array

Массив, из которого берётся значение.

Возвращаемые значения

Возвращает значение последнего элемента массива array.
Если array пуст, будет возвращён null.

Примеры

Пример #1 Пример использования array_pop()


<?php
$stack = array("orange", "banana", "apple", "raspberry");
$fruit = array_pop($stack);
print_r($stack);
?>

После этого в $stack будет только 3 элемента: 

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
)

и raspberry будет присвоено переменной
$fruit.

Смотрите также

  • array_push() – Добавляет один или несколько элементов в конец массива
  • array_shift() – Извлекает первый элемент массива
  • array_unshift() – Добавляет один или несколько элементов в начало массива

elad dot yosifon at gmail dot com

9 years ago


Notice:
the complexity of array_pop() is O(1).
the complexity of array_shift() is O(n).
array_shift() requires a re-index process on the array, so it has to run over all the elements and index them.

noreply at i-asm dot com

2 years ago


Note that array_pop doesn't issue ANY warning or error if the array is already empty when you try to pop something from it. This is bizarre! And it will cause cascades of errors that are hard to resolve without knowing the real cause.

Rather than an error, it silently returns a NULL object, it appears, so in my case I ended up with warnings elsewhere about accessing elements of arrays with invalid indexes, as I was expecting to have popped an array. This behaviour (and the lack of any warning, when many trivial things are complained about verbosely) is NOT noted in the manual above. Popping an already empty stack should definitely trigger some sort of notice, to help debugging.

Sure, it's probably good practice to wrap the pop in an if (count($array)) but that should be suggested in the manual, if there's no error returned for trying something that should fail and obviously isn't expected to return a meaningful result.


mcgroovin at gmail dot com

14 years ago


I wrote a simple function to perform an intersect on multiple (unlimited) arrays.

Pass an array containing all the arrays you want to compare, along with what key to match by.

<?php

function multipleArrayIntersect($arrayOfArrays, $matchKey)

{

    $compareArray = array_pop($arrayOfArrays);

   
    foreach(

$compareArray AS $key => $valueArray){

        foreach($arrayOfArrays AS $subArray => $contents){

            if (!in_array($compareArray[$key][$matchKey], $contents)){

                unset($compareArray[$key]);

            }

        }

    }

    return

$compareArray;

}

?>


rmondragon at gmail dot com

17 years ago


In a previous example ...
<?php
function array_trim ( $array, $index ) {
   if ( is_array ( $array ) ) {
     unset ( $array[$index] );
     array_unshift ( $array, array_shift ( $array ) );
     return $array;
     }
   else {
     return false;
     }
   }
?>

This have a problem. if u unset the last value and then use
<?
array_unshift ( $array, array_shift ( $array ) );
?>

will return a :  Array ( [0] => )
so u can fix it using...

<?php
if (count($array) > 0) array_unshift ( $values, array_shift ( $values ) );           
?>

good luck ;)


Alex Chac?n

20 years ago


alex.chacon@terra.com

Hi

Here there is a function that delete a elemente from a array and re calculate indexes

<?php

function eliminarElementoArreglo ($array, $indice)

{

    if (array_key_exists($indice, $array))

    {

        $temp = $array[0];

        $array[0] = $array[$indice];

        $array[$indice] = $temp;

        array_shift($array);
//reacomodamos ?ndices

        for ($i = 0 ; $i < $indice ; $i++)

        {

            $dummy = $array[$i];

            $array[$i] = $temp;

            $temp = $dummy;

        }

    }

    return $array;

}

?>


doyley3731 at gmail dot com

15 years ago


I had a problem when using this function because my array was made up entirley of numbers, so I have made my own function.  Hopefully it will be useful to somebody.

function array_trim_end($array){

$num=count($array);
$num=$num-1;
unset($array[$num]);

return $array;
}


qeremy

11 years ago


For the sake of array_unshift()
:)

<?php
function array_unpop(&$arr) {
    $args = func_get_args(); unset($args[0]);
    $tarr = array();
    foreach ($args as $arg) {
        $tarr[] = $arg;
    }
    $arr = array_merge($arr, $tarr);
}$queue = array("orange", "banana");
array_unpop($queue, "apple", "raspberry");
print_r($queue);
?>

Array
(
    [0] => orange
    [1] => banana
    [2] => apple
    [3] => raspberry
)


Anonymous

9 years ago


Strict Standards will be thrown out if you put exploded array in array_pop:
<?php
$a = array_pop(explode(",", "a,b,c"));
echo $a;
?>

You will see:
PHP Strict Standards:  Only variables should be passed by reference in - on line 2

Strict Standards: Only variables should be passed by reference in - on line 2
c

Notice that, you should assign a variable for function explode, then pass the variable reference into array_pop to avoid the Strict Standard warning.


sonetti at hotmail dot com

15 years ago


@smp_info
I think you are still tired. What would be wrong with:

<?php
$array = array('one', 'two', 'three', 'four');//pop the last element off
array_pop($array);//$array == array('one', 'two', 'three');
?>

As the documentation clearly notes, array_pop() not only returns the last element, but actually removes it from the array wich is passed by reference. Calling array_diff is a waste of resources.


Anonymous

18 years ago


strrchr is a lot more useful than the other example using array_pop for finding the extension of a file. For example:

<?php
$ext = strrchr($filename, ".");
?>

$ext will contain the extension of the file, including a ".", if the file has an extension, and FALSE if the file has no extension. If the file has multiple extensions, such as "filename.tar.gz", then this construction will just return the last extension.


Orsi

15 years ago


Hi,

Here is a simple function which delete one element from the array (with value):
<?php
/*
* This function deletes the given element from a one-dimension array
* Parameters: $array:    the array (in/out)
*             $deleteIt: the value which we would like to delete
*             $useOldKeys: if it is false then the function will re-index the array (from 0, 1, ...)
*                          if it is true: the function will keep the old keys
* Returns true, if this value was in the array, otherwise false (in this case the array is same as before)
*/
function deleteFromArray(&$array, $deleteIt, $useOldKeys = FALSE)
{
    $tmpArray = array();
    $found = FALSE;
    foreach($array as $key => $value)
    {
        if($value !== $deleteIt)
        {
            if(FALSE === $useOldKeys)
            {
                $tmpArray[] = $value;
            }
            else
            {
                $tmpArray[$key] = $value;
            }
        }
        else
        {
            $found = TRUE;
        }
    }$array = $tmpArray;

       return

$found;
}
?>

Maybe it will help somebody...


Источник

I have to find last value of that array

The length property is at least one higher than the highest index, however it might be higher in which case the n-1 member may not exist. E.g.

// Create an array with length 10
var a = new Array(10);

// Add one member at index 0
a[0] = 'foo';

So the “last” value of the array is at index 0 and has a value of “foo”. So you can start with length – 1 and search backwards for members that actually exist:

function lastValue(arr) {
  var i = arr.length;
  while (i--) {
    if (i in arr) {
      return arr[i];
    }
  }
  // If get to here, arr has no members
  return -1;
}

// All the following arrays have length 4 but different number of members
console.log(lastValue([ , , , ,]));  // -1, i.e. there are no members
console.log(lastValue([0,1, , ,]));  //  1
console.log(lastValue([0,1,2,3 ]));  //  3
console.log(lastValue([ , , ,3 ]));  //  3

If you know the Array only has numeric members (i.e. there are no non-numeric properties and no negative properties) you can do:

var arr = [,,'foo',,'bar',,]; // length 6, highest member is at index 4

console.log(arr[Math.max.apply(Math, Object.keys(arr))]); // 'bar'

Requires ES5 Object.keys.

Источник

В этом посте мы обсудим, как получить последний элемент массива в JavaScript.

1. Использование [] оператор

Рекомендуемое решение для получения любого элемента массива — использование [] оператор. Чтобы получить последний элемент, просто передайте его индекс в [] оператора, как показано ниже:

const arr = [ 5, 3, 2, 7, 8 ];

const last = arr[arr.length–1];

console.log(last);

/*

    результат: 8

*/

Скачать  Выполнить код

2. Использование присваивания деструктуризации

Другим хорошим решением является использование Присвоение деструктуризации синтаксис для получения последнего элемента массива. Следующий пример кода демонстрирует его использование:

const arr = [ 5, 3, 2, 7, 8 ];

const [last] = arr.slice(–1);

console.log(last);

/*

    результат: 8

*/

Скачать  Выполнить код

3. Использование Array.prototype.pop() функция

The pop() метод возвращает последний элемент из массива, но также удаляет его из массива. Чтобы избежать изменения исходного массива, рассмотрите возможность создания копии массива перед вызовом pop() метод. Вы можете сделать это двумя способами:

⮚ Нарезка

const arr = [ 5, 3, 2, 7, 8 ];

const last = arr.slice(–1).pop();

console.log(last);

/*

    результат: 8

*/

Скачать  Выполнить код

⮚ Оператор спреда ES6

const arr = [ 5, 3, 2, 7, 8 ];

const last = [...arr].pop();        // не рекомендуется для больших массивов

console.log(last);

/*

    результат: 8

*/

Скачать  Выполнить код

4. Использование библиотеки Underscore/Lodash

Кроме того, с библиотекой Underscore или Lodash JavaScript вы можете использовать параметр no-arg. _.last метод, который возвращает последний элемент массива.

const _ = require(‘underscore’);

const arr = [ 5, 3, 2, 7, 8 ];

const last = _.last(arr);

console.log(last);

/*

    результат: 8

*/

Скачать код

5. Использование jQuery

С помощью jQuery вы можете передать индекс -1 к .get(index) чтобы получить последний элемент.

const arr = [ 5, 3, 2, 7, 8 ];

const last = $(arr).get(–1);

console.log(last);

/*

    результат: 8

*/

Вот и все, что касается получения последнего элемента массива в JavaScript.

Спасибо за чтение.

Пожалуйста, используйте наш онлайн-компилятор размещать код в комментариях, используя C, C++, Java, Python, JavaScript, C#, PHP и многие другие популярные языки программирования.

Как мы? Порекомендуйте нас своим друзьям и помогите нам расти. Удачного кодирования 🙂

Источник

Если необходимо получить значение последнего элемента массива, то это можно сделать просто обратившись по индексу. Индексом будет длина массивам минус один:

const numbers = [1, 2, 3];
const item = numbers[numbers.length - 1];
console.log(item); // => 3

Есть встроенный метод pop(), который извлекает последний элемент из массива и при этом удаляет этот элемент в исходном массиве:

const numbers = [1, 2, 3];
const item = numbers.pop();
console.log(item); // => 3
console.log(numbers); // => [1, 2]
Источник

Добавить комментарий