---
title: WindowBase64
slug: Web/API/WindowBase64
tags:
  - API
translation_of: Web/API/WindowOrWorkerGlobalScope
translation_of_original: Web/API/WindowBase64
---
<p>{{APIRef("HTML DOM")}}</p>

<p>The <code><strong>WindowBase64</strong></code> helper contains utility methods to convert data to and from base64, a binary-to-text encoding scheme. For example it is used in <a href="/en-US/docs/data_URIs">data URIs</a>.</p>

<p>There is no object of this type, though the context object, either the {{domxref("Window")}} for regular browsing scope, or the {{domxref("WorkerGlobalScope")}}  for workers, implements it.</p>

<h2 id="Properties">Properties</h2>

<p><em>This helper neither defines nor inherits any properties.</em></p>

<h2 id="Methods">Methods</h2>

<p><em>This helper does not inherit any methods.</em></p>

<dl>
 <dt>{{domxref("WindowBase64.atob()")}}</dt>
 <dd>Decodes a string of data which has been encoded using base-64 encoding.</dd>
 <dt>{{domxref("WindowBase64.btoa()")}}</dt>
 <dd>Creates a base-64 encoded ASCII string from a string of binary data.</dd>
</dl>

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

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('HTML WHATWG', '#windowbase64', 'WindowBase64')}}</td>
   <td>{{Spec2('HTML WHATWG')}}</td>
   <td>No change since the latest snapshot, {{SpecName("HTML5.1")}}.</td>
  </tr>
  <tr>
   <td>{{SpecName('HTML5.1', '#windowbase64', 'WindowBase64')}}</td>
   <td>{{Spec2('HTML5.1')}}</td>
   <td>Snapshot of {{SpecName("HTML WHATWG")}}. No change.</td>
  </tr>
  <tr>
   <td>{{SpecName("HTML5 W3C", "#windowbase64", "WindowBase64")}}</td>
   <td>{{Spec2('HTML5 W3C')}}</td>
   <td>Snapshot of {{SpecName("HTML WHATWG")}}. Creation of <code>WindowBase64</code> (properties where on the target before it).</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>{{CompatibilityTable}}</p>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox (Gecko)</th>
   <th>Chrome</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatGeckoDesktop(1)}} [1]</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>10.0</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Android</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatGeckoMobile(1)}}</td>
   <td rowspan="1">{{CompatVersionUnknown}}</td>
   <td rowspan="1">{{CompatVersionUnknown}}</td>
   <td rowspan="1">{{CompatVersionUnknown}}</td>
   <td rowspan="1">{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<p>[1]  <code>atob()</code> is also available to XPCOM components implemented in JavaScript, even though {{domxref("Window")}} is not the global object in components.</p>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/Web/API/WindowBase64/Base64_encoding_and_decoding">Base64 encoding and decoding</a></li>
 <li>{{domxref("Window")}}, {{domxref("WorkerGlobalScope")}}, {{domxref("DedicatedWorkerGlobalScope")}}, {{domxref("SharedWorkerGlobalScope")}}, and {{domxref("ServiceWorkerGlobalScope")}}</li>
</ul>