Using content preferences

  • Revision slug: Using_content_preferences
  • Revision title: Using content preferences
  • Revision id: 71930
  • Created:
  • Creator: Sheppy
  • Is current revision? No
  • Comment 1 words added, 1 words removed

Revision Content

{{ Fx_minversion_header("3") }} Firefox 3 introduces the concept of content preferences. This permits code running within chrome (in other words: extensions and the browser itself, not web sites) to locally save preferences on a per-site basis. This makes it possible to write an extension that lets the user customize the appearance of specific web sites (setting the font size larger on sites that use obnoxiously small fonts, for instance).

The content preferences service, implemented by {{ Interface("nsIContentPrefService") }}, offers functions for setting and retrieving preferences for specific sites or in the global preference space; global preferences are used whenever a site-specific preference isn't available.

Site-specific content preferences are stored in the profile folder, in the database file "content-prefs.sqlite".

{{ Fx_minversion_note("3") }}

Example: Setting and retrieving preferences

This example demonstrates how to save a preference and then retrieve its value.

var ioSvc = Components.classes["@mozilla.org/network/io-service;1"]
            .getService(Components.interfaces.nsIIOService);
var prefService = Components.classes["@mozilla.org/content-pref/service;1"]
                  .getService(Components.interfaces.nsIContentPrefService);

// Create a URI object referencing the site to save a preference for
var uri = ioSvc.newURI("http://developer.mozilla.org/", null, null);

// Set the value of the "devmo.somesetting" preference to "foo".

prefService.setPref(uri, "devmo.somesetting", "foo");

...

// Retrieve the value of the "devmo.somesetting" preference.

var value = prefService.getPref(uri, "devmo.somesetting");

Built-in site-specific preference in Firefox 3.5

Preference Name Menu Equivalent Values Notes
browser.content.full-zoom View / Zoom Example: "1.10000002384186"
(Rounding variant of "1.1")
Related about:config preferences:
  • browser.zoom.full
    Boolean, set by the menu item
    View / Zoom / Zoom Text Only.
    Despite the confusion in names, this preference is not site-specific.
  • browser.zoom.siteSpecific
  • toolkit.zoomManager.zoomValues
  • zoom.maxPercent and zoom.minPercent

See also

  • {{ Interface("nsIContentPrefService") }}
  • {{ Interface("nsIContentPrefObserver") }}
  • toSource() (potentially useful for serializing objects for later use with eval())

 

{{ languages( { "es": "es/Usar_las_preferencias_de_contenido", "fr": "fr/Utilisation_des_pr\u00e9f\u00e9rences_de_contenu", "ja": "ja/Using_content_preferences" } ) }}

Revision Source

<p>{{ Fx_minversion_header("3") }} Firefox 3 introduces the concept of content preferences. This permits code running within chrome (in other words: extensions and the browser itself, not web sites) to locally save preferences on a per-site basis. This makes it possible to write an extension that lets the user customize the appearance of specific web sites (setting the font size larger on sites that use obnoxiously small fonts, for instance).</p>
<p>The content preferences service, implemented by {{ Interface("nsIContentPrefService") }}, offers functions for setting and retrieving preferences for specific sites or in the global preference space; global preferences are used whenever a site-specific preference isn't available.</p>
<p>Site-specific content preferences are stored in the profile folder, in the database file "content-prefs.sqlite".</p>
<p>{{ Fx_minversion_note("3") }}</p>
<h3 name="Example:_Setting_and_retrieving_preferences">Example: Setting and retrieving preferences</h3>
<p>This example demonstrates how to save a preference and then retrieve its value.</p>
<pre class="eval">var ioSvc = Components.classes["@mozilla.org/network/io-service;1"]
            .getService(Components.interfaces.nsIIOService);
var prefService = Components.classes["@mozilla.org/content-pref/service;1"]
                  .getService(Components.interfaces.nsIContentPrefService);

// Create a URI object referencing the site to save a preference for
var uri = ioSvc.newURI("<span class="nowiki">http://developer.mozilla.org/</span>", null, null);

// Set the value of the "devmo.somesetting" preference to "foo".

prefService.setPref(uri, "devmo.somesetting", "foo");

...

// Retrieve the value of the "devmo.somesetting" preference.

var value = prefService.getPref(uri, "devmo.somesetting");
</pre>
<h3>Built-in site-specific preference in Firefox 3.5</h3>
<table class="standard-table"> <tbody> <tr> <td class="header">Preference Name</td> <td class="header">Menu Equivalent</td> <td class="header">Values</td> <td class="header">Notes</td> </tr> <tr> <td><code>browser.content.full-zoom</code></td> <td>View / Zoom</td> <td><em>Example:</em> "1.10000002384186"<br> (Rounding variant of "1.1")</td> <td>Related about:config preferences: <ul> <li><code>browser.zoom.full</code><br> Boolean, set by the menu item<br> View / Zoom / Zoom Text Only.<br> Despite the confusion in names, this preference is not site-specific.</li> <li><code>browser.zoom.siteSpecific</code></li> <li><code>toolkit.zoomManager.zoomValues</code></li> <li> <p><code>zoom.maxPercent and </code><code>zoom.minPercent</code></p> </li> </ul> </td> </tr> </tbody>
</table>
<h3 name="See_also">See also</h3>
<ul> <li>{{ Interface("nsIContentPrefService") }}</li> <li>{{ Interface("nsIContentPrefObserver") }}</li> <li><a href="/en/Core_JavaScript_1.5_Reference/Global_Objects/Object/toSource" title="en/Core_JavaScript_1.5_Reference/Global_Objects/Object/toSource">toSource()</a> (potentially useful for serializing objects for later use with <a href="/en/Core_JavaScript_1.5_Reference/Functions/eval" title="en/Core_JavaScript_1.5_Reference/Functions/eval">eval()</a>)</li>
</ul>
<p> </p>
<p>{{ languages( { "es": "es/Usar_las_preferencias_de_contenido", "fr": "fr/Utilisation_des_pr\u00e9f\u00e9rences_de_contenu", "ja": "ja/Using_content_preferences" } ) }}</p>
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