For fengari-web[1] we want to watch for <script type="text/lua"> tags inserted into the document. At the moment we use a MutationObserver[2], but I should compare the speed of things. I've created a new issue to track[3]

  [1] https://github.com/fengari-lua/fengari-web
  [2] https://github.com/fengari-lua/fengari-web/blob/4279f4b3aec063062eb8baf68a065ee5b0c1d7c6/src/fengari-web.js#L132
  [3] https://github.com/fengari-lua/fengari-web/issues/15