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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
+original_slug: Web/JavaScript/Referencje/Obiekty/Array/keys
+---
+<div>{{JSRef}}</div>
+
+<p>Metoda <code><strong>keys()</strong></code> zwraca nowy obiekt typu <code><strong>Array Iterator</strong></code> zawierający indeksy kolejnych elementów tablicy.</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="Składnia">Składnia</h2>
+
+<pre class="syntaxbox"><var>arr</var>.keys()</pre>
+
+<h3 id="Zwracana_wartość">Zwracana wartość</h3>
+
+<p>Nowy iterator dla typu {{jsxref("Array")}}.</p>
+
+<h2 id="Przykłady">Przykłady</h2>
+
+<h3 id="Iterator_nie_ignoruje_dziur">Iterator nie ignoruje dziur</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="Specyfikacje">Specyfikacje</h2>
+
+<table class="standard-table">
+ <tbody>
+  <tr>
+   <th scope="col">Specyfikacja</th>
+   <th scope="col">Status</th>
+   <th scope="col">Komentarz</th>
+  </tr>
+  <tr>
+   <td>{{SpecName('ES2015', '#sec-array.prototype.keys', 'Array.prototype.keys')}}</td>
+   <td>{{Spec2('ES2015')}}</td>
+   <td>Pierwsze wystąpienie.</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="Kompatybilność_z_przeglądarkami">Kompatybilność z przeglądarkami</h2>
+
+<div>{{CompatibilityTable}}</div>
+
+<div id="compat-desktop">
+<table class="compat-table">
+ <tbody>
+  <tr>
+   <th>Feature</th>
+   <th>Chrome</th>
+   <th>Firefox (Gecko)</th>
+   <th>Edge</th>
+   <th>Internet Explorer</th>
+   <th>Opera</th>
+   <th>Safari</th>
+  </tr>
+  <tr>
+   <td>Basic support</td>
+   <td>{{CompatChrome("38")}}</td>
+   <td>{{CompatGeckoDesktop("28")}}</td>
+   <td>{{CompatVersionUnknown}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatOpera("25")}}</td>
+   <td>{{CompatSafari("7.1")}}</td>
+  </tr>
+ </tbody>
+</table>
+</div>
+
+<div id="compat-mobile">
+<table class="compat-table">
+ <tbody>
+  <tr>
+   <th>Feature</th>
+   <th>Android</th>
+   <th>Chrome for Android</th>
+   <th>Firefox Mobile (Gecko)</th>
+   <th>IE Mobile</th>
+   <th>Opera Mobile</th>
+   <th>Safari Mobile</th>
+  </tr>
+  <tr>
+   <td>Basic support</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatGeckoMobile("28")}}</td>
+   <td>{{CompatNo}}</td>
+   <td>{{CompatNo}}</td>
+   <td>8.0</td>
+  </tr>
+ </tbody>
+</table>
+</div>
+
+<h2 id="Zobacz_również">Zobacz również</h2>
+
+<ul>
+ <li>{{jsxref("Array.prototype.values()")}}</li>
+ <li>{{jsxref("Array.prototype.entries()")}}</li>
+ <li>{{jsxref("Iteration_protocols", "Iteratory")}}</li>
+</ul>