I just installed the new Android Studio and I\'m looking for a way to be able to get support for CSS and JS (autocomplete, highlighting for incorrect usages) as i would in P
JS/CSS are not part of Android Studio. You'd have to install IntelliJ Ultimate edition if you need those.
In general, you won't get a feature like that which is only available in a paid version in a free tool like Android Studio or IntelliJ Community Edition.