DocumentDB: How to define a callback function in stored procedures when using JavaScript Language Integrated Query?

The documentation states the equivalence of the below code snippets. But in the former case, I can perform operations on the collection of documents inside the callback function, while the display function in the latter only works on one document. I want to group document values, which I could do in a callback, but not in a map function. Is there a way to do this with "JavaScript Language Integrated Query"? And how would I configure the response body correctly?

    __.queryDocuments(__.getSelfLink(),
          "SELECT docs.id, docs.message AS msg " +
          "FROM docs " +
          "WHERE docs.id='X998_Y998'"
        ,
        function(err, docs, options) {
          __.response.setBody(docs);
        });

      

        
        
        
      

    

and

__.chain()
    .filter(function(doc) {
        return doc.id === "X998_Y998";
    })
    .map(function(doc) {
        return {
            id: doc.id,
            msg: doc.message
        };
    })
    .value();