Lex Trotman - 2014-02-17

Unless you select "autocomplete all words" only the symbols extracted from the source or from loaded global tags files are autocompleted. For HTML the "symbols" are the contents of the h1-6 tags and a few others. These autocomplete correctly. As an HTML only special case the entity names (from file html_entities.tags) are offered in the completion list, but are not autocompletions so you need to use the manual completion as you noted.

Embedded Javascript, PHP, etc is not parsed, the system does not support mixed languages. Whilst developing you can keep the js in a separate file and load it with the src attribute on the script tag. The js will then be parsed and autocomplete should work.

Changing this is indeed a feature request, possibly a big one, contributions are welcome :)