Unlike goog.provide packages, goog.module modules are loaded using
XMLHttpRequest in uncompiled mode. Because browsers treat file: URLs
as each being a separate, unique origin, this means that CORS rules
prevent goog.module modules being loaded from a file URL.
To work around this, use the http-server npm to serve the repository
root directory on localhost:8080.
Provide a script so that you can type `npm start` to start the local
http server and automatically open a browser window pointing at
tests/playground.html.
Modify the setBackgroundColour function in the playgrounds to provide
the usual lilac background on locahost URLs and a sickly green one
if using a file: URL, all of which will soon stop working.
(The background doesn't actually appear to be visible in the advanced
playground.)
* Use local node_modules files instead of unkpkg for advanced playground, get test blocks in the basic playground from npm
* Also move theme-modern
* Update package-lock
