Learning PHP and WordPress

Apparently, even with creating WordPress theme, you don't really have to learn PHP much.

The only way to learn PHP well seems to be by creating a new CMS. Although, you might learn a little with some CMS, such as Bolt CMS.

Injecting unsafe HTML into Bolt entries + CodeMirror/UIKit editor

By default, both Markdown field and HTML field is available for Bolt CMS, but sanitation is done before inserting into the database, making rendering of certain elements impossible; especially, for those starting with < (Unless you use &lt;).

So, I fixed this while preserving the editor (CodeMirror/UIKit) here.

Learning PHP from other programming languages

PHP is a bit different from other languages, like Python or Dart, in that, it is a mainly a web programming language, running on a server. Furthermore, it is actually pre-installed in macOS.

I would actually recommend this -- https://phptherightway.com/, and it is quite updated.