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Pole JavaScript lastIndexOf()

Příklady

Najděte poslední index "Apple":

const fruits = ["Apple", "Orange", "Apple", "Mango"];
let index = fruits.lastIndexOf("Apple");

Více než jedno jablko:

const fruits = ["Orange", "Apple", "Mango", "Apple", "Banana", "Apple"];
let index = fruits.lastIndexOf("Apple");

Další příklady níže.


Definice a použití

Metoda lastIndexOf()vrací poslední index (pozici) zadané hodnoty.

Pokud hodnota lastIndexOf()není nalezena, metoda vrátí -1.

Začíná lastIndexOf()na zadaném indexu a vyhledává zprava doleva.

Výchozím nastavením vyhledávání začíná u posledního prvku a končí u prvního.

Záporné počáteční hodnoty se počítají od posledního prvku (ale stále se vyhledává zprava doleva).

Viz také:

indexOf()


Syntax

array.lastIndexOf(item, start)

Parametry

Parameter Description
item Required.
The value to search for.
start Optional.
Where to start the search.
Default is the last element (array.length-1).
Negative start values counts from the last element (but still searches from right to left).

Návratová hodnota

Typ Popis
ČísloPozice zadané položky.
-1, pokud položka není nalezena.


Podpora prohlížeče

lastIndexOf() je funkce ECMAScript5 (ES5).

ES5 (JavaScript 2009) plně podporován ve všech prohlížečích:

Chrome IE Edge Firefox Safari Opera
Yes 9-11 Yes Yes Yes Yes

Další příklady

Začněte hledat na pozici 4:

const fruits = ["Orange", "Apple", "Mango", "Apple", "Banana", "Apple"];
let index = fruits.lastIndexOf("Apple", 4);

Začněte hledat na předposlední pozici:

const fruits = ["Orange", "Apple", "Mango", "Apple", "Banana", "Apple"];
let index = fruits.lastIndexOf("Apple", -2);