code: function(array, propertyName) {
              var ret = [],
                  i, ln, item;
  
              for (i = 0, ln = array.length; i < ln; i++) {
                  item = array[i];
  
                  ret.push(item[propertyName]);
              }
  
              return ret;
          }
docs: Plucks the value of a property from each item in the Array. Example:
  
  Ext.Array.pluck(Ext.query("p"), "className"); // [el1.className, el2.className, ..., elN.className]
  
  @param {Array/NodeList} array The Array of items to pluck the value from.
  @param {String} propertyName The property name to pluck from each element.
  @return {Array} The value from each item in the Array.