上述与以下代码相同：
function Circle(xPoint,yPoint,radius) {
 this.x = xPoint;
 this.y = yPoint;
 this.r = radius;
}

Circle.prototype.pi = Math.PI;
function Circle.prototype.area() {
 return this.pi*this.r*this.r;
}
//Circle.prototype.area = circleArea;

function getCircleArea(x,y,r) {
 aCircle = new Circle(x,y,r);
 return aCircle.area();
}

===========================================================
var Try = {
  these: function() {
    var returnValue;

    for (var i = 0; i < arguments.length; i++) {
      var lambda = arguments[i];
      try {
        returnValue = lambda();
        break;
      } catch (e) {}
    }

    return returnValue;
  }
}

var Ajax = {
  getTransport: function() {
    return Try.these(
      function() {return new ActiveXObject('Msxml2.XMLHTTP')},
      function() {return new ActiveXObject('Microsoft.XMLHTTP')},
      function() {return new XMLHttpRequest()}
    ) || false;
  },

  activeRequestCount: 0
}

================================================================
用原型方法（用prototype定义）在大量定义对象的时候会比较节省资源。也可以在系统的类(如String)上面附加新的方法。
function String.prototype.trim()
 {
 return  this.replace(/(^\s*)|(\s*$)/g, "");
 }
alert("  abcd  ".trim());

    if (document.implementation && document.implementation.createDocument) {
        // This is the W3C standard way to do it
        return document.implementation.createDocument(namespaceURL,
                                                      rootTagName, null);
    }
    else { // This is the IE way to do it
        // Create an empty document as an ActiveX object
        // If there is no root element, this is all we have to do
        var doc = new ActiveXObject("MSXML2.DOMDocument");

        // If there is a root tag, initialize the document
        if (rootTagName) {
            // Look for a namespace prefix
            var prefix = "";
            var tagname = rootTagName;
            var p = rootTagName.indexOf(':');
            if (p != -1) {
                prefix = rootTagName.substring(0, p);
                tagname = rootTagName.substring(p+1);
            }

            // If we have a namespace, we must have a namespace prefix
            // If we don't have a namespace, we discard any prefix
            if (namespaceURL) {
                if (!prefix) prefix = "a0"; // What Firefox uses
            }
            else prefix = "";

            // Create the root element (with optional namespace) as a
            // string of text
            var text = "<" + (prefix?(prefix+":"):"") +  tagname +
                (namespaceURL
                 ?(" xmlns:" + prefix + '="' + namespaceURL +'"')
                 :"") +
                "/>";
            // And parse that text into the empty document
            doc.loadXML(text);
        }
        return doc;
    }
};

function loadFromUrl(url) {
    // Create a new document with the previously defined function
    var xmldoc = XML.newDocument( );
    xmldoc.async = false;  // We want to load synchronously
    xmldoc.load(url);      // Load and parse
    return xmldoc;         // Return the document
}

function xmlToString(xmlDoc)
{
    var xmlString;
    try
    {
        if (navigator.appName == "Microsoft Internet Explorer")
        {
            xmlString = xmlDoc.xml;
        }
        else
        {
            xmlString = new XMLSerializer().serializeToString( xmlDoc );
        }
    }
    catch (e)
    {
        xmlString = null;
    }
    return xmlString;
}

function stringToXMLDoc(str)
{
    var xmlDoc = null;
    try
    {
        var xmlDOMObj = new ActiveXObject("Microsoft.XMLDOM");
        xmlDOMObj.async = false;
        xmlDOMObj.loadXML(str);
        xmlDoc = xmlDOMObj;
    }
    catch (e)
    {
        try
        {
            var domParser = new DOMParser;
            xmlDoc = domParser.parseFromString(str, 'text/xml');
        }
        catch (e)
        {
            xmlDoc = null;
        }
    }
    return xmlDoc;

}

function stringToXMLDoc(str) {
    if (typeof DOMParser != "undefined") {
        // Mozilla, Firefox, and related browsers
        return (new DOMParser( )).parseFromString(text, "application/xml");
    }
    else if (typeof ActiveXObject != "undefined") {
        // Internet Explorer.
        var doc = XML.newDocument( );  // Create an empty document
        doc.loadXML(text);            // Parse text into it
        return doc;                   // Return it
    }
    else {
        // As a last resort, try loading the document from a data: URL
        // This is supposed to work in Safari. Thanks to Manos Batsis and
        // his Sarissa library (sarissa.sourceforge.net) for this technique.
        var url = "data:text/xml;charset=utf-8," + encodeURIComponent(text);
        var request = new XMLHttpRequest( );
        request.open("GET", url, false);
        request.send(null);
        return request.responseXML;
    }
}

 this.cmpTabId = null;
 this.cmpTableId = null;
 this.funcTableId = null;

 this.currData = new Array();
 this.OUTLOOK = new Array();
 this.selectedArray = new Array();
 this.criterionArray = new Array();
  
 this.parseAllData = ComParserAllDataSub;
 this.sepArray = ComSepArraySub;
 this.initComTable = ComInitComTableSub;

 this.checkAllChild = ComCheckAllChildSub;
 this.checkParent = ComCheckParentSub;
 this.addselectedFC = ComAddselectedFCSub;

 this.generateXML = ComgenerateXMLSub;
 this.parserArray = ComparserArraySub;

 this.editFunc = ComEditFunc;
}


function InitAllSub(cmpId,allData,allDataEdit,tableType)
{
 if(allData == null || allData.length == 0)
 {
  _alertMsg += "This is no fap!";
  return;
 }
 var obj = new CE_CompanyObjSub(cmpId,allData,allDataEdit,tableType);
 cmSubArray.push(obj);
 obj.parseAllData();
 obj.sepArray();
 obj.initComTable();
 
 if(allDataEdit == null || allDataEdit.length == 0)
  return;
  
 obj.editFunc();
}

function ComParserAllDataSub()
{
 this.currData = this.allData; 
}

function ComSepArraySub()
{
      var strCon=20;
   TransStatus="Ready";
      WorkWindow=top.work;
      CommonData=top.commondata;
      WorkWindowSet=top.bottomwork;
      moduseq=-1;
      grpseq=-1;
      funcseq=-1;
      modulen=0;
      grplen=0;
        
       for(i=0;i<this.currData.length;i++)
          {
    varmoduId = this.currData[i][0];
    varmodu = this.currData[i][1];
    varfuncId = this.currData[i][2];
    varfunc = this.currData[i][3];
    if(bar)
     varfuncDesc = this.currData[i][4];
   
   
       modulen=this.OUTLOOK.length;
          for(m=0;m<modulen;m++)
       {
        if(this.OUTLOOK[m][0]==varmoduId + ":" + varmodu)
        {
                       moduseq=m;
                      grplen=this.OUTLOOK[m].length;
                      for(n=1;n<grplen;n++)
                         {
                             if(this.OUTLOOK[m][n][0]==varfuncId + ":" + varfunc + ":" + varfuncDesc)
                             {
                                grpseq=n;
                                break;
                             }
                         }
         }
       }
    if(moduseq==-1)
    {
          this.OUTLOOK[modulen]=new Array();
          this.OUTLOOK[modulen][0]=varmoduId + ":" + varmodu;
          this.OUTLOOK[modulen][1]=new Array();
          this.OUTLOOK[modulen][1][0]=varfuncId + ":" + varfunc + ":" + varfuncDesc;
          moduseq=modulen;
          grpseq=1;
     }
     else
     {
         if(grpseq==-1)
         {
            grpseq=this.OUTLOOK[moduseq].length;
            this.OUTLOOK[moduseq][grpseq]=new Array();
            this.OUTLOOK[moduseq][grpseq][0]=varfuncId + ":" + varfunc + ":" + varfuncDesc;
            }
     }
    moduseq=-1;
    grpseq=-1;
   }
  
}

         function low(imgLow){
               low=imgLow;
               clearInterval(highlighting);
                lowlighting = setInterval("lowLight(low)",100);
         }

         function highlightit(img){
             if(img.filters.alpha.opacity < 200) {
              img.filters.alpha.opacity += 5;
             }
             //else if (window.highlighting)
              //clearInterval(highlighting);
         }
         function lowLight(img) {
             if(img.filters.alpha.opacity > 15)
                    img.filters.alpha.opacity -= 5;
             //else if (window.lowlighting)
              //clearInterval(lowlighting);
         }
         网页打开后，第一次鼠标移上去渐清晰，移走后也正常逐渐消失，都很正常。可当我再次把鼠标移到图片上时，就没有反应了，在移出图片时JS报错，说在<img />那行，对象不支持此属性或方法。
        调了好久也没成功，特来向大家请教！