Execute function from String in node.js

Is there a way to execute a function from String passed as a request parameter and return result in node.js ? Imagine a request which contains String:

"db.users.find()"

as a parameter

If I knew I wanted to execute this statement I would do this:

db.collection('users', function(err, collection) {
    collection.find().toArray(function(err, items) {
        res.send(items);
    });
});

What I want is something like a parser which would execute given statement and returned results.

I tried like this:

exports.execStatement = function(req, res) {
//var statemnet = req.params.statement;
  var statement = "collection.find().toArray(function(err, items) {
        res.send(items);});";
  db.collection('users', function(err, collection) {        
    eval(statement)
   });
};

This code gives me error:

var statement = "collection.find().toArray(function(err, prdel) { ...
SyntaxError: Unexpected token ILLEGAL

What is wrong ? Why can't I execute code stored in a String ? After this works I would like to figure out how to execute code which is passed as a parameter in request.

Is this approach even possible ?