I'm new to developing with WebStorm and don't understand the difference between adding an original library with a global scope (e.g. jquery.js) either from the local file system or by downloading it via the Download button (from the Official libraries list) and adding a so-called TypeScript community stub for jquery (all via Settings... -> Languages & Frameworks -> JavaScript -> Libraries). Both give me code completion, but what is the difference and what is preferable?
And why TypeScript when we are dealing with JavaScript only?