How are you adding that Javascript? Are you editing a PHP file in core moodle or a plugin, or are you just trying to get it through the HTML editor? If editing-plugin/hacking-core you are on the right track though getting non AMD modules to play nicely with requirejs can be tricky.
Anyway, the Generico filter was created for purposes like this, where you just need a little front end insert and do not want to create a whole new plugin. You create templates and add your external javacript links in there. Perhaps check it out and see if it helps.
https://moodle.org/plugins/filter_generico
There are quite a few templates available as examples. Some of them are here: