chrome/common/extensions/docs/templates/articles/app_deprecated.html

<h1>Disabled Web Features</h1>
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<p>
Though packaged apps use the web platform,
some web features have been disabled
or else are used in a different way.
Mainly this is to avoid security issues and
to improve programming practices.
Below is a summary of the disabled features
of the web platform
and potential work-arounds:
</p>

<table border="0">
  <tr>
    <th scope="col"> Disabled </th>
    <th scope="col"> Work-around </th>
  </tr>
  <tr>
    <td><code>alert</code></td>
    <td>Use a custom lightbox/popup.</td>
  </tr>
  <tr>
    <td>Browser chrome APIs</td>
    <td>N/A.</td>
  </tr>
  <tr>
    <td><code>confirm</code></td>
    <td>Use a custom lightbox/popup.</td>
  </tr>
  <tr>
    <td><code>document.cookie</code></td>
    <td>Packaged app pages are not rendered on the server, so there is no need to use these.</td>
  </tr>
  <tr>
    <td><code>document.close</code></td>
    <td>N/A.</td>
  </tr>
  <tr>
    <td><code>document.open</code></td>
    <td>N/A.</td>
  </tr>
  <tr>
    <td><code>document.write</code></td>
    <td>Use document.createElement.</td>
  </tr>
  <tr>
    <td>External resources</td>
    <td>Use the <code>object</code> tag for iframes
      See <a href="app_external.html">Embed Content</a>.
      Video and audio are allowed to have non-local URLs.</td>
  </tr>
  <tr>
    <td>Flash</td>
    <td>Use HTML5 Platform.</td>
  </tr>
  <tr>
    <td>Form submission</td>
    <td>Use JavaScript to process form content
      (listen for submit event, process data locally first
      before sending to server).</td>
  </tr>
  <tr>
    <td>javascript: urls</td>
    <td>You cannot use bookmarklets for inline javascript on anchors.
      Use the traditional click handler instead.</td>
  </tr>
  <tr>
    <td>localStorage</td>
    <td>Use IndexedDB or the Storage API (which also syncs to the cloud).</td>
  </tr>
  <tr>
    <td>Navigation</td>
    <td>Links open up with the system web browser.
      <code>window.history</code> and <code>window.location</code>
      are disabled.</td>
  </tr>
  <tr>
    <td>Non-sandboxed plugins</td>
    <td>N/A.</td>
  </tr>
  <tr>
    <td><code>showModalDialog</code></td>
    <td>Use a custom lightbox/popup.</td>
  </tr>
  <tr>
    <td>Synchronous <code>XMLHttpRequest</code></td>
    <td>Use async-only <code>XMLHttpRequest</code>:
      <a href="http://updates.html5rocks.com/2012/01/Getting-Rid-of-Synchronous-XHRs">Getting Rid of Synchrounous XXRs</a>.</td>
  </tr>
  <tr>
    <td>webSql</td>
    <td>Use IndexedDB or
      <a href="app_storage.html">Filesystem API</a>.</td>
  </tr>
</table>

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