Retrieve the related entity Data using Javascript (json)

 In this example it will retrieve the related sales order detail for a specific sales order ..

retirevesalesorderdetails :function () {  var GUIDvalue = Xrm.Page.data.entity.getId();  var serverUrl = Xrm.Page.context.getServerUrl();  var req = new XMLHttpRequest(); req.open("GET", serverUrl +   "/XRMServices/2011/OrganizationData.svc/SalesOrderSet(guid'" + GUIDvalue + "')/order_details", true); //order_details is the relationship with the sales order and sales order details   req.setRequestHeader("Accept", "application/json");   req.setRequestHeader("Content-Type", "application/json; charset=utf-8");   req.onreadystatechange = function () {      if (this.readyState == 4 /* complete */) {             if (this.status == 200) {                         var returned = JSON.parse(this.responseText,_dateReviver).d;                         successCallback(returned.results);                          if (returned.__next != null) { }                          else { OnComplete(); } }                          else { errorCallback(_errorHandler(this)); }                    }                };      req.send();  } _dateReviver: function (key, value) {     ///     /// Private function to convert matching string values to Date objects.     ///     ///     /// The key used to identify the object property     ///     ///     /// The string value representing a date     ///     var a;     if (typeof value === 'string') {         a = /Date\(([-+]?\d+)\)/.exec(value);         if (a) {             return new Date(parseInt(value.replace("/Date(", "").replace(")/", ""), 10));         }     }     return value; } function errorHandler(error) {     writeMessage(error.message); } function successCallback(results) {     for (var i = 0; i <= results.length; i++) {         var Result = results[i];         if (Result != null) {                   var ProductId = Result.tci_productid;             var SalesQty = Result.quantity;   }  } } function OnComplete() {     //OnComplete handler }

Note :- in this you have to add the json2.js libaray also for the parsing to happen .. it is available with CRM 2011 SDK