JXA is nuts

linkfileHandler.js

// Use this with https://onflapp.wordpress.com/lincastor/
// Lets you create double-clickable relative links in MacOS that sync over google drive and such.
// A "link" is just a text file with a relative path.

var app = Application.currentApplication();
app.includeStandardAdditions = true;

function readUrl(url) {
  var urlObj = $.NSURL.alloc.initWithString(url);
	return $.NSString.alloc.initWithContentsOfURL(urlObj).UTF8String.trim();
}

function relativeUrl(base, relative) {
  var baseUrl = $.NSURL.alloc.initWithString(base);
  return $.NSURL.alloc.initWithStringRelativeToURL(relative, baseUrl);
}

function handle_url (args) {  
  var linkContents = readUrl(args.URL);
  var target = relativeUrl(args.URL, linkContents);
  var url = target.absoluteString.UTF8String;
  app.openLocation(url);
  return 1;
}