Il metodo keys() ritorna un nuovo oggetto Array Iterator contenente le chiavi di ogni indice dell'array.

var arr = ['a', 'b', 'c'];
var iterator = arr.keys();

console.log(iterator.next()); // { value: 0, done: false }
console.log(iterator.next()); // { value: 1, done: false }
console.log(iterator.next()); // { value: 2, done: false }
console.log(iterator.next()); // { value: undefined, done: true }

Sintassi

arr.keys()

Valore di ritorno

Un nuovo oggetto Array.

Esempi

I Key iterator non ignorano gli elementi vuoti

var arr = ['a', , 'c'];
var sparseKeys = Object.keys(arr);
var denseKeys = [...arr.keys()];
console.log(sparseKeys); // ['0', '2']
console.log(denseKeys);  // [0, 1, 2]

Specifiche

Specifica Stato Commenti
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Array.prototype.keys' in that specification.
Standard Initial definition.
ECMAScript Latest Draft (ECMA-262)
The definition of 'Array.prototype.keys' in that specification.
Draft  

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung InternetNode.js
Basic supportChrome Full support 38Edge Full support YesFirefox Full support 28IE No support NoOpera Full support 25Safari Full support 8WebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support 28Opera Android Full support YesSafari iOS Full support 8Samsung Internet Android Full support Yesnodejs Full support 0.12

Legend

Full support  
Full support
No support  
No support

Vedi anche

Tag del documento e collaboratori

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