Using content preferences

  • Revision slug: Using_content_preferences
  • Revision title: Using content preferences
  • Revision id: 71924
  • Created:
  • Creator: Mgjbot
  • Is current revision? No
  • Comment robot Adding: [[es:Usar las preferencias de contenido]] <<langbot>>

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.

{{ 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");

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>{{ 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 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">toSource()</a> (potentially useful for serializing objects for later use with <a href="en/Core_JavaScript_1.5_Reference/Functions/eval">eval()</a>)
</li></ul>
<p><br>
</p>
<div class="noinclude">
</div>
{{ languages( { "es": "es/Usar_las_preferencias_de_contenido", "fr": "fr/Utilisation_des_pr\u00e9f\u00e9rences_de_contenu", "ja": "ja/Using_content_preferences" } ) }}
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