CRM 2011 "$ is undefined"

Question

I have created following code, and I have included this as web resource on the CRM 2011 form to be called on field onchange event of lookup field. Everything is working fine before the $.ajax({... line and then I have an error “$ is undefined”. I am not very familiar with scripting so please help.

function GetAddress() {

    var accountId;
    var dataArray;
    var accountRequestUrl;

    if (crmForm.all.regardingobjectid.DataValue != null) {

        dataArray = crmForm.all.regardingobjectid.DataValue;
        accountId = dataArray[0].id;

        if (typeof GetGlobalContext == "function") {
            var context = GetGlobalContext();
            accountRequestUrl = context.getServerUrl();
        }
        else {
            if (typeof Xrm.Page.context == "object") {
                accountRequestUrl = Xrm.Page.context.getServerUrl();
            }
        }

        accountRequestUrl = Xrm.Page.context.getServerUrl();
        accountRequestUrl += "/XRMServices/2011/OrganizationData.svc/AccountSet(guid'" +
            accountId + "')";

        crmForm.all.maxlife_addressname.DataValue = accountRequestUrl;

        GetAccountRecord(accountRequestUrl);
    }
    else {
        alert("null");
    }

}

function GetAccountRecord(accountRequestUrl) {

    $.ajax({
        type: "GET",
        url: accountRequestUrl,
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        error: function (request, textStatus, errorThrown) {
            alert("Error occurred: " + request.responseXML + "from url " + requestUrl);
            return;
        },
        success: function (data) {
            var results = data.d["results"];
            var AccountValue = new Array();
            for (resultKey in results) {
                AccountValue.push(results[resultKey]);
            }

            FillValues(AccountValue);
        }
    });
}

Answer 1

$ is shorthand for jQuery. jQuery is not natively included in CRM2011, so you'll have to add a web reference yourself. Simply create a JavaScript web resource for jQuery, paste in the jQuery code, and then add the web resource to your form. Also, in order to get the web resource to load on your form, you need to specify a function for CRM to call from it. Since in this case jQuery is a library and you won't be calling any of its functions onload, simply use isNaN (a native JavaScript function) as the function to call.