GetIndividualItems.js

that._getData = function (navTermID, listName, xmlQuery, contentType, onGetSuccess) {
    var objClientCtx = new SP.ClientContext.get_current();            //can be reused
    if (objClientCtx) {
        var oList = objClientCtx.get_web().get_lists().getByTitle(listName);
        var query = new SP.CamlQuery();
        query.set_viewXml(xmlQuery);
        var objlistItems = oList.getItems(query);
        objClientCtx.load(objlistItems);
        objClientCtx.executeQueryAsync(function (sender, args) {
            that.DataSet = [];
            var objlistEnumerator = objlistItems.getEnumerator();
            while (objlistEnumerator.moveNext()) {
                var objListItem = objlistEnumerator.get_current();
                var firstName = objListItem.get_item('FirstName');
                var lastName = objListItem.get_item('LastName');
                var email = objListItem.get_item('Email');
                
                that.DataSet.push({
                    "FirstName": firstName,
                    "LastName": lastName,
                    "Email": email,
                });

            }
            onGetSuccess(that.DataSet);

        }, function (sender, args) {
            that._onGetFail(sender, args);
        });
    }
}