I use VS Code for my Visual Studio Magazine articles and have customized my environment to do this in HTML files, but I've always wanted quick-hit macros to automate tedious tasks. That's "quick hit" ...

If you have an existing web application, open it in Visual Studio Code (preferably copying it to a new development branch) and then use the PWA Studio tools to convert it into a PWA.

Not only can you integrate JavaScript with Blazor, that integration provides a strategy for moving your existing pages to Blazor without having to rewrite your existing JavaScript code.