When I hire juniors I give them problems that focus on fundamentals. If a junior can code vanilla JS well, they can learn React, Vue, Svelte, etc. if they can

When I hire juniors I give them problems that focus on fundamentals. If a junior can code vanilla JS well, they can learn React, Vue, Svelte, etc. if they can't, they will never fully understand any of them. If they can write raw CSS, that can learn Tailwind and understand how and why. If thry can explain what's happening in the browser console, they can find the entry point for most bugs. This is pretty much how I also test seniors. Focus on the fundamentals; if those are off, nothing else matters.