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   1  /*
   2   * Metadata - jQuery plugin for parsing metadata from elements
   3   *
   4   * Copyright (c) 2006 John Resig, Yehuda Katz, J�örn Zaefferer, Paul McLanahan
   5   *
   6   * Dual licensed under the MIT and GPL licenses:
   7   *   http://www.opensource.org/licenses/mit-license.php
   8   *   http://www.gnu.org/licenses/gpl.html
   9   *
  10   *
  11   */
  12  
  13  /**
  14   * Sets the type of metadata to use. Metadata is encoded in JSON, and each property
  15   * in the JSON will become a property of the element itself.
  16   *
  17   * There are four supported types of metadata storage:
  18   *
  19   *   attr:  Inside an attribute. The name parameter indicates *which* attribute.
  20   *          
  21   *   class: Inside the class attribute, wrapped in curly braces: { }
  22   *   
  23   *   elem:  Inside a child element (e.g. a script tag). The
  24   *          name parameter indicates *which* element.
  25   *   html5: Values are stored in data-* attributes.
  26   *          
  27   * The metadata for an element is loaded the first time the element is accessed via jQuery.
  28   *
  29   * As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
  30   * matched by expr, then redefine the metadata type and run another $(expr) for other elements.
  31   * 
  32   * @name $.metadata.setType
  33   *
  34   * @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
  35   * @before $.metadata.setType("class")
  36   * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
  37   * @desc Reads metadata from the class attribute
  38   * 
  39   * @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
  40   * @before $.metadata.setType("attr", "data")
  41   * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
  42   * @desc Reads metadata from a "data" attribute
  43   * 
  44   * @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
  45   * @before $.metadata.setType("elem", "script")
  46   * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
  47   * @desc Reads metadata from a nested script element
  48   * 
  49   * @example <p id="one" class="some_class" data-item_id="1" data-item_label="Label">This is a p</p>
  50   * @before $.metadata.setType("html5")
  51   * @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
  52   * @desc Reads metadata from a series of data-* attributes
  53   *
  54   * @param String type The encoding type
  55   * @param String name The name of the attribute to be used to get metadata (optional)
  56   * @cat Plugins/Metadata
  57   * @descr Sets the type of encoding to be used when loading metadata for the first time
  58   * @type undefined
  59   * @see metadata()
  60   */
  61  
  62  (function($) {
  63  
  64  $.extend({
  65    metadata : {
  66      defaults : {
  67        type: 'class',
  68        name: 'metadata',
  69        cre: /({.*})/,
  70        single: 'metadata'
  71      },
  72      setType: function( type, name ){
  73        this.defaults.type = type;
  74        this.defaults.name = name;
  75      },
  76      get: function( elem, opts ){
  77        var settings = $.extend({},this.defaults,opts);
  78        // check for empty string in single property
  79        if ( !settings.single.length ) settings.single = 'metadata';
  80        
  81        var data = $.data(elem, settings.single);
  82        // returned cached data if it already exists
  83        if ( data ) return data;
  84        
  85        data = "{}";
  86        
  87        var getData = function(data) {
  88          if(typeof data != "string") return data;
  89          
  90          if( data.indexOf('{') < 0 ) {
  91            data = eval("(" + data + ")");
  92          }
  93        }
  94        
  95        var getObject = function(data) {
  96          if(typeof data != "string") return data;
  97          
  98          data = eval("(" + data + ")");
  99          return data;
 100        }
 101        
 102        if ( settings.type == "html5" ) {
 103          var object = {};
 104          $( elem.attributes ).each(function() {
 105            var name = this.nodeName;
 106            if(name.match(/^data-/)) name = name.replace(/^data-/, '');
 107            else return true;
 108            object[name] = getObject(this.nodeValue);
 109          });
 110        } else {
 111          if ( settings.type == "class" ) {
 112            var m = settings.cre.exec( elem.className );
 113            if ( m )
 114              data = m[1];
 115          } else if ( settings.type == "elem" ) {
 116            if( !elem.getElementsByTagName ) return;
 117            var e = elem.getElementsByTagName(settings.name);
 118            if ( e.length )
 119              data = $.trim(e[0].innerHTML);
 120          } else if ( elem.getAttribute != undefined ) {
 121            var attr = elem.getAttribute( settings.name );
 122            if ( attr )
 123              data = attr;
 124          }
 125          object = getObject(data.indexOf("{") < 0 ? "{" + data + "}" : data);
 126        }
 127        
 128        $.data( elem, settings.single, object );
 129        return object;
 130      }
 131    }
 132  });
 133  
 134  /**
 135   * Returns the metadata object for the first member of the jQuery object.
 136   *
 137   * @name metadata
 138   * @descr Returns element's metadata object
 139   * @param Object opts An object contianing settings to override the defaults
 140   * @type jQuery
 141   * @cat Plugins/Metadata
 142   */
 143  $.fn.metadata = function( opts ){
 144    return $.metadata.get( this[0], opts );
 145  };
 146  
 147  })(jQuery);