I haven't used Typescript but I've generally heard very good things about it. I didn't know you can mix and match, that might give me a bit more of kick to include it in a project, thanks.

Whether or not it's an advantage of Javascript… I'm not sure. I mean, if someone wrote a transpiler for Java that overlayed stricter typing, would that really be an advantage of Java? Not sure, but of course, worth considering when choosing a language for a project.