Get all Messages from Discussions List via SharePoint CSOM

getMessages.js

function getMessages(listTitle,disscussionId,OnItemsLoaded,OnError)
{
    var context = new SP.ClientContext.get_current();
    var web = context.get_web();
 
    var list = web.get_lists().getByTitle(listTitle);
    context.load(list);
   
    var qry = createAllMessagesByDisscussionIDQuery(disscussionId);
    var messageItems = list.getItems(qry);
    context.load(messageItems);
   
    context.executeQueryAsync(
        function() {
          OnItemsLoaded(messageItems);           
        },
        OnError
    );
}

function createAllMessagesByDisscussionIDQuery(disscussionId) {
    var qry = new SP.CamlQuery;
    var viewXml = "<View Scope='Recursive'> \
                <Query> \
                    <Where> \
                        <Eq> \
                            <FieldRef Name='ParentFolderId' /> \
                            <Value Type='Integer'>" + disscussionId + "</Value> \
                        </Eq> \
                    </Where> \
                </Query> \
            </View>";
    qry.set_viewXml(viewXml);        
    return qry;
};