Comment directives are quite common in JavaScript world, ESlint being the 800-pound gorilla in the room using these, TSchecker being its little sibling, but other languages use them as well. In fact, TypeScript, which is a superset of JS and by no means a niche language, uses triple-slash /// exactly for this purpose, to include files: ///<reference path="./mydir/myfile" />
I find you guys' opposition very unfortunate. Yes, we are very happy that you are listening to users and adding new features, but some of these additions break language rules. There is nothing remotely similar to @-directives or ==SCRIPT RESOURCES in JS or JScript world. Remember this thread about maps? I had requested the change because it broke JS rule that one cannot use RHS statement as LHS value. This is the same problem all over again. @pro is right about it, if the added feature is relatively new, it can be still adjusted.
If //@include looks weird to you (to me it doesn't, not one bit), then why not use more JS-like syntax like: var mylib = require('mylib.js) or import * as mylib from "mylib.js"?