var requestData = { __batchRequests: [ { __changeRequests: [
{ requestUri: "Customers", method: "POST", headers: { "Content-ID": "1" }, data: {
    CustomerID: 400, CustomerName: "John"
}  }
] } ] };

var requestData = {};
requestData.__batchRequests = [];
requestData.__batchRequests[0] = {};
requestData.__batchRequests[0].__changeRequests = [];
requestData.__batchRequests[0].__changeRequests[0] = {};
requestData.__batchRequests[0].__changeRequests[0].requestUri = "Customers";
requestData.__batchRequests[0].__changeRequests[0].method = "POST";
requestData.__batchRequests[0].__changeRequests[0].headers = { "Content-ID" : "1" };
requestData.__batchRequests[0].__changeRequests[0].data = {};

var changeRequest = {
    requestUri : "Customers",
    method : "POST",
    headers : { "Content-ID" : "1" },
    data : {}
};

requestData.__batchRequests[0].__changeRequests.push(changeRequest);

changeRequest.data.CustomerName = "Bob";
changeRequest.data.CustomerID = "204";


requestData.__/*...*/changeRequests[0].data.CustomerName; // Bob

function extend (obj, additions) {
    var key;
    for (key in obj) { if (additions.hasOwnProperty(key)) {
        obj[key] = additions[key];
    }
}

function makeChangeRequest (url, method, headers, data) {
    var request = {
        requestUri : url,
        method : method,
        headers : {},
        data : {}
    };

    extend(request.headers, headers);
    extend(request.data, data);

    return request;
}

function getBatch (num) { return requestData.__batchRequests[num]; }


var changeReq = makeChangeRequest("Customers",
                                  "POST",
                                  { "Content-ID" : "1" },
                                  { CustomerName : "Bob", CustomerID : "2012" });

var batch = getBatch(0);

batch.__changeRequests.push(changeReq);

extend(changeReq.data, { Address : "33 Nowhere Rd.", City : "Splitsville" });

var requestData = { __batchRequests: [ { __changeRequests: [
{ requestUri: "Customers", method: "POST", headers: { "Content-ID": "1" }, data: {}  }
] } ] };

var customerDeetsArray =[{CustomerID: 400}, {CustomerName: "John"}];

for (var i in customerDeetsArray) {
  requestData.data = $.extend(requestData.data, customerDeetsArray[i]);
}