Currently none of the top JavaScript SPA frameworks (Angular, React & Vue) are supported/available in Webuilder 2020. And no highlighting support for JavaScript derivates like JSX and TypeScript.
This should be available in new version (and not added years later, like the Bootstrap framework support) if the editor should be up-to-date with the current JavaScript usage like other editors on the market. Otherwise Webuilder will fail to attract serious coders and just end up as a glorified Notepad clone.