I don't think it is such an obvious yes that it's unproductive or wrong to start with 'basics', or fundamentals. Learning MDN/Javascript.info will get you far

I don't think it is such an obvious yes that it's unproductive or wrong to start with 'basics', or fundamentals. Learning MDN/Javascript.info will get you far wrt. JS. The best-practices/current-year-way of writing React will change like 5 times before you're done with fundamentals and you've probably missed nothing.