---
title: String.prototype.repeat()
slug: Web/JavaScript/Reference/Global_Objects/String/repeat
translation_of: Web/JavaScript/Reference/Global_Objects/String/repeat
original_slug: Web/JavaScript/Referencje/Obiekty/String/repeat
---
<div>{{JSRef}}</div>

<p>The <strong><code>repeat()</code></strong> method constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together.</p>

<h2 id="Składnia">Składnia</h2>

<pre class="syntaxbox"><var>str</var>.repeat(<var>count</var>)</pre>

<h3 id="Parametry">Parametry</h3>

<dl>
 <dt><code>count</code></dt>
 <dd>An integer between 0 and +∞: [0, +∞), indicating the number of times to repeat the string in the newly-created string that is to be returned.</dd>
</dl>

<h3 id="Zwracana_wartość">Zwracana wartość</h3>

<p>A new string containing the specified number of copies of the given string.</p>

<h3 id="Exceptions">Exceptions</h3>

<ul>
 <li>{{jsxref("Errors/Negative_repetition_count", "RangeError")}}: repeat count must be non-negative.</li>
 <li>{{jsxref("Errors/Resulting_string_too_large", "RangeError")}}: repeat count must be less than infinity and not overflow maximum string size.</li>
</ul>

<h2 id="Przykłady">Przykłady</h2>

<pre class="brush: js">'abc'.repeat(-1);   // RangeError
'abc'.repeat(0);    // ''
'abc'.repeat(1);    // 'abc'
'abc'.repeat(2);    // 'abcabc'
'abc'.repeat(3.5);  // 'abcabcabc' (count will be converted to integer)
'abc'.repeat(1/0);  // RangeError

({ toString: () =&gt; 'abc', repeat: String.prototype.repeat }).repeat(2);
// 'abcabc' (repeat() is a generic method)
</pre>

<h2 id="Polyfill">Polyfill</h2>

<p>This method has been added to the ECMAScript 6 specification and may not be available in all JavaScript implementations yet. However, you can polyfill <code>String.prototype.repeat()</code> with the following snippet:</p>

<pre class="brush: js">if (!String.prototype.repeat) {
  String.prototype.repeat = function(count) {
    'use strict';
    if (this == null) {
      throw new TypeError('can\'t convert ' + this + ' to object');
    }
    var str = '' + this;
    count = +count;
    if (count != count) {
      count = 0;
    }
    if (count &lt; 0) {
      throw new RangeError('repeat count must be non-negative');
    }
    if (count == Infinity) {
      throw new RangeError('repeat count must be less than infinity');
    }
    count = Math.floor(count);
    if (str.length == 0 || count == 0) {
      return '';
    }
    // Ensuring count is a 31-bit integer allows us to heavily optimize the
    // main part. But anyway, most current (August 2014) browsers can't handle
    // strings 1 &lt;&lt; 28 chars or longer, so:
    if (str.length * count &gt;= 1 &lt;&lt; 28) {
      throw new RangeError('repeat count must not overflow maximum string size');
    }
    var rpt = '';
    for (;;) {
      if ((count &amp; 1) == 1) {
        rpt += str;
      }
      count &gt;&gt;&gt;= 1;
      if (count == 0) {
        break;
      }
      str += str;
    }
    // Could we try:
    // return Array(count + 1).join(this);
    return rpt;
  }
}
</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-string.prototype.repeat', 'String.prototype.repeat')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td>Initial definition.</td>
  </tr>
  <tr>
   <td>{{SpecName('ESDraft', '#sec-string.prototype.repeat', 'String.prototype.repeat')}}</td>
   <td>{{Spec2('ESDraft')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</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>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome("41")}} </td>
   <td>{{CompatGeckoDesktop("24")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatSafari("9")}}</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>{{CompatChrome("36")}}</td>
   <td>{{CompatGeckoMobile("24")}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>