If you often embed other languages into JS template literals (and you use VSCode) then I have the extension for you.
This baby lets you hit a shortcut, pops open a tab with just the contents of your template literal, and sets the syntax mode accordingly. Now you have full editor support for the given language!
It syncs everything you type back to the original file and saving the tab just saves the original file. It’s a lil weird, sure, but kinda neat.
https://marketplace.visualstudio.com/items?itemName=plievone.vscode-template-literal-editor