// 讓 firefox 支援 loadXML, selectSingleNode, selectNodes, .text
if( document.implementation.hasFeature("XPath", "3.0") )
{
    XMLDocument.prototype.loadXML = function(xmlString)
    {
        var childNodes = this.childNodes;
        for (var i = childNodes.length - 1; i >= 0; i--)
            this.removeChild(childNodes[i]);

        var dp = new DOMParser();
        var newDOM = dp.parseFromString(xmlString, "text/xml");
        var newElt = this.importNode(newDOM.documentElement, true);
        this.appendChild(newElt);
    };
}

// check for XPath implementation
if( document.implementation.hasFeature("XPath", "3.0") )
{
    // prototying the XMLDocument
    XMLDocument.prototype.selectNodes = function(cXPathString, xNode)
    {
      if( !xNode ) { xNode = this; } 
      var oNSResolver = this.createNSResolver(this.documentElement)
      var aItems = this.evaluate(cXPathString, xNode, oNSResolver, 
                   XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null)
      var aResult = [];
      for( var i = 0; i < aItems.snapshotLength; i++)
      {
         aResult[i] =  aItems.snapshotItem(i);
      }
      return aResult;
   }

   // prototying the Element
   Element.prototype.selectNodes = function(cXPathString)
   {
      if(this.ownerDocument.selectNodes)
      {
         return this.ownerDocument.selectNodes(cXPathString, this);
      }
      else{throw "For XML Elements Only";}
   }
}

// check for XPath implementation
if( document.implementation.hasFeature("XPath", "3.0") )
{
   // prototying the XMLDocument
   XMLDocument.prototype.selectSingleNode = function(cXPathString, xNode)
   {
      if( !xNode ) { xNode = this; } 
      var xItems = this.selectNodes(cXPathString, xNode);
      if( xItems.length > 0 )
      {
         return xItems[0];
      }
      else
      {
         return null;
      }
   }

   // prototying the Element
   Element.prototype.selectSingleNode = function(cXPathString)
   {    
      if(this.ownerDocument.selectSingleNode)
      {
         return this.ownerDocument.selectSingleNode(cXPathString, this);
      }
      else{throw "For XML Elements Only";}
   }
   
   Element.prototype.text = "";
}