I doubt this is possible. Since JavaScript is 'loosely typed' it's not possible to know of what type a variable is in a certain part of the script without actually running it.

Example:

var s;
function myOtherFunction() {
s = "Not MyObject anymore";
}

function myFunction() {
s = new MyObject();

s.
// You'd probably expect a list of available methods
// for 'MyObject' here

function myOtherFunction();

s.
// There's no way of knowing that s has become a
// string without actually running the script.

}