How do search engines deal with AngularJS applications?

Question

I see two issues with AngularJS application regarding search engines and SEO:

1) What happens with custom tags? Do search engines ignore the whole content within tho

Answer 1

With Angular Universal, you can generate landing pages for the app that look like the complete app and then load your Angular app behind it.
Angular Universal generates pure HTML means no-javascript pages in server-side and serve them to users without delaying. So you can deal with any crawler, bot and user (who already have low cpu and network speed).Then you can redirect them by links/buttons to your actual angular app that already loaded behind it. This solution is recommended by official site. -More info about SEO and Angular Universal-