function DoStuff(foo) //<<<<No information what type foo is { foo.DoA(); //No way to know what methods foo support foo.DoB(); } For most situatio

function DoStuff(foo) //<<<<No information what type foo is { foo.DoA(); //No way to know what methods foo support foo.DoB(); } For most situations where it is possible to infer the type, Visual studio actually does a pretty good job on code completion, but no jump to definition.