using OData in Javascript MS CRM 2013

Here is code  for how to fetch entity records from JavaScript Using OData
use Schema names for field names

function MainFunction()
{
    var project = getLookupId("ap_project");
    if (project != null) {
        var filter = "&$filter=";
        filter += "ap_projectId eq guid'" + project + "'";
        var odataQuery = "/ap_projectSet?$select=ap_projectId,ap_TypeOfContract" + filter;
        ExecuteQuery(odataQuery, true, function (data) {
            if (data && data.d && data.d.results && data.d.results[0])
           {
               // Get Results here
                       var typeofcontract = data.d.results[0].yourfieldname.Value;
              
            }
        });
    }
}

function ExecuteQuery(odataQuery, sync, callback) {
    var async = true;
    if (sync) {
        async = false;
    }
    var odataPath = Xrm.Page.context.getClientUrl() + "/XRMServices/2011/OrganizationData.svc";
    var odataUrl = odataPath + odataQuery;
    $.ajax({
        type: "GET",
        contentType: "application/json; charset=utf-8",
        datatype: "json",
        url: odataUrl,
        async: async,
        beforeSend: function (xmlHttpRequest) {
            xmlHttpRequest.setRequestHeader("Accept", "application/json");
        },
        success: function (data, textStatus, xmlHttpRequest) {
            if (callback) {
                callback(data);
            }
        },
        error: function (xmlHttpRequest, textStatus, errorObject) {
            alert("Error Occurred : " + textStatus + ": " + JSON.parse(xmlHttpRequest.responseText).error.message.value);
        }
    });
}

function getLookupId(lookupName) {
    var lookupItem = new Array();
    lookupItem = Xrm.Page.getAttribute(lookupName).getValue();
    if (lookupItem != null) {
        return lookupItem[0].id;
    }
    else
        return null;
}