jquery.metadata.js

/*
 * Metadata - jQuery plugin for parsing metadata from elements
 *
 * Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
 *
 * Dual licensed under the MIT and GPL licenses:
 *   http://www.opensource.org/licenses/mit-license.php
 *   http://www.gnu.org/licenses/gpl.html
 *
 * Revision: $Id: jquery.metadata.js 3640 2007-10-11 18:34:38Z pmclanahan $
 *
 */

/**
 * Sets the type of metadata to use. Metadata is encoded in JSON, and each property
 * in the JSON will become a property of the element itself.
 *
 * There are four supported types of metadata storage:
 *
 *   attr:  Inside an attribute. The name parameter indicates *which* attribute.
 *          
 *   class: Inside the class attribute, wrapped in curly braces: { }
 *   
 *   elem:  Inside a child element (e.g. a script tag). The
 *          name parameter indicates *which* element.
 *   html5: Values are stored in data-* attributes.
 *          
 * The metadata for an element is loaded the first time the element is accessed via jQuery.
 *
 * As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
 * matched by expr, then redefine the metadata type and run another $(expr) for other elements.
 * 
 * @name $.metadata.setType
 *
 * @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
 * @before $.metadata.setType("class")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from the class attribute
 * 
 * @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
 * @before $.metadata.setType("attr", "data")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a "data" attribute
 * 
 * @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
 * @before $.metadata.setType("elem", "script")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a nested script element
 * 
 * @example <p id="one" class="some_class" data-item_id="1" data-item_label="Label">This is a p</p>
 * @before $.metadata.setType("html5")
 * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
 * @desc Reads metadata from a series of data-* attributes
 *
 * @param String type The encoding type
 * @param String name The name of the attribute to be used to get metadata (optional)
 * @cat Plugins/Metadata
 * @descr Sets the type of encoding to be used when loading metadata for the first time
 * @type undefined
 * @see metadata()
 */

(function($) {

$.extend({
  metadata : {
    defaults : {
      type: 'class',
      name: 'metadata',
      cre: /({.*})/,
      single: 'metadata'
    },
    setType: function( type, name ){
      this.defaults.type = type;
      this.defaults.name = name;
    },
    get: function( elem, opts ){
      var settings = $.extend({},this.defaults,opts);
      // check for empty string in single property
      if ( !settings.single.length ) settings.single = 'metadata';
      
      var data = $.data(elem, settings.single);
      // returned cached data if it already exists
      if ( data ) return data;
      
      data = "{}";
      
      var getData = function(data) {
        if(typeof data != "string") return data;
        
        if( data.indexOf('{') < 0 ) {
          data = eval("(" + data + ")");
        }
      }
      
      var getObject = function(data) {
        if(typeof data != "string") return data;
        
        data = eval("(" + data + ")");
        return data;
      }
      
      if ( settings.type == "html5" ) {
        var object = {};
        $( elem.attributes ).each(function() {
          var name = this.nodeName;
          if(name.match(/^data-/)) name = name.replace(/^data-/, '');
          else return true;
          object[name] = getObject(this.nodeValue);
        });
      } else {
        if ( settings.type == "class" ) {
          var m = settings.cre.exec( elem.className );
          if ( m )
            data = m[1];
        } else if ( settings.type == "elem" ) {
          if( !elem.getElementsByTagName ) return;
          var e = elem.getElementsByTagName(settings.name);
          if ( e.length )
            data = $.trim(e[0].innerHTML);
        } else if ( elem.getAttribute != undefined ) {
          var attr = elem.getAttribute( settings.name );
          if ( attr )
            data = attr;
        }
        object = getObject(data.indexOf("{") < 0 ? "{" + data + "}" : data);
      }
      
      $.data( elem, settings.single, object );
      return object;
    }
  }
});

/**
 * Returns the metadata object for the first member of the jQuery object.
 *
 * @name metadata
 * @descr Returns element's metadata object
 * @param Object opts An object contianing settings to override the defaults
 * @type jQuery
 * @cat Plugins/Metadata
 */
$.fn.metadata = function( opts ){
  return $.metadata.get( this[0], opts );
};

})(jQuery);