Invoking WCF Service through Javascript

How can I access the WCF Service through JavaScript? My problem is, I have to access the operation contracts through the JavaScript (my website is not Ajax enabled).
Previously for calling .asmx web services, I am using the following code snippet

var xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
xmlHttp.open("POST", URL, false);
xmlHttp.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xmlHttp.send(payload);
xmlData = xmlHttp.responseXML;

where url is my webservice location.

Now if I am trying to consume the wcf service in the same manner, I am not able to. Many techies are explaining through AJAX approach, I need an approach without AJAX.

From stackoverflow

• By using XMLHTTP you ARE using ajax.

  There's a full example here:

  jQuery AJAX calls to a WCF REST Service

• ThankQ for your reply.

  Can't I use the same code to invoke the WCF Service

  var xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
  xmlHttp.open("POST", URL, false);
  xmlHttp.setRequestHeader("Content-Type",
        "application/x-www-form-urlencoded");xmlHttp.send(payload);
  xmlData = xmlHttp.responseXML;
  

  Previously while invoking the webservices the service url is like this Customers.asmx/GetCustomer?CustomerID=1794

  Can i use the same approach to invoke the wcf service Customers.svc/GetCustomer?CustomerID=1794

  i have gone throught the link that you have posted, but i should not use any third party files(json2.js) sorry for that.

  If possilbe Please suggest me the changes in the above code to proceed further with wcf services

• Look at the code on the link that I have sent before. Sure U can implement it yourself but it well be a huge effort duplication.

  First, your WCF service must have:

  [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
  

  Then, on the javascript side, change the

  "Content-Type", "application/x-www-form-urlencoded"
  

  To

  "Content-Type", "application/json"
  

  Remember that the response will be json formated, so having a parser could be useful.

  Why you don't want to use external libs?