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+---
+title: Array.prototype.keys()
+slug: Web/JavaScript/Reference/Global_Objects/Array/keys
+translation_of: Web/JavaScript/Reference/Global_Objects/Array/keys
+---
+<div>{{JSRef}}</div>
+
+<p>Il metodo <code><strong>keys()</strong></code> ritorna un nuovo oggetto <code><strong>Array Iterator</strong></code> contenente le chiavi di ogni indice dell'array.</p>
+
+<pre class="brush: js">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 }
+</pre>
+
+<h2 id="Sintassi">Sintassi</h2>
+
+<pre class="syntaxbox"><var>arr</var>.keys()</pre>
+
+<h3 id="Valore_di_ritorno">Valore di ritorno</h3>
+
+<p>Un nuovo oggetto {{jsxref("Array")}}.</p>
+
+<h2 id="Esempi">Esempi</h2>
+
+<h3 id="I_Key_iterator_non_ignorano_gli_elementi_vuoti">I Key iterator non ignorano gli elementi vuoti</h3>
+
+<pre class="brush: js">var arr = ['a', , 'c'];
+var sparseKeys = Object.keys(arr);
+var denseKeys = [...arr.keys()];
+console.log(sparseKeys); // ['0', '2']
+console.log(denseKeys); // [0, 1, 2]
+</pre>
+
+<h2 id="Specifiche">Specifiche</h2>
+
+<table class="standard-table">
+ <tbody>
+ <tr>
+ <th scope="col">Specifica</th>
+ <th scope="col">Stato</th>
+ <th scope="col">Commenti</th>
+ </tr>
+ <tr>
+ <td>{{SpecName('ES2015', '#sec-array.prototype.keys', 'Array.prototype.keys')}}</td>
+ <td>{{Spec2('ES2015')}}</td>
+ <td>Initial definition.</td>
+ </tr>
+ <tr>
+ <td>{{SpecName('ESDraft', '#sec-array.prototype.keys', 'Array.prototype.keys')}}</td>
+ <td>{{Spec2('ESDraft')}}</td>
+ <td> </td>
+ </tr>
+ </tbody>
+</table>
+
+<h2 id="Browser_compatibility">Browser compatibility</h2>
+
+<div>
+
+
+<p>{{Compat("javascript.builtins.Array.keys")}}</p>
+</div>
+
+<h2 id="Vedi_anche">Vedi anche</h2>
+
+<ul>
+ <li>{{jsxref("Array.prototype.values()")}}</li>
+ <li>{{jsxref("Array.prototype.entries()")}}</li>
+ <li><a href="/en-US/docs/Web/JavaScript/Reference/Iteration_protocols">Iteration protocols</a></li>
+</ul>