Ask HN: What are best resources to learn new programming language as senior dev?

I am developer with about 10 years of experience in PHP and Linux server administration (basically managing and creating software for LAMP/LEMP stack). Looking at job offers recently I noticed decline in PHP roles therefore I started to look around for good, fast paced online courses that will help me get up to speed with new and shiny languages/frameworks that are seeing bigger demand (JS, Node, Python, Go etc.). The problem is that virtually all of those curses are targeted at beginners, spending hours on explaining how loops and if statements works. During last 10 years I wrote a lot of code not only in PHP but occasionally some bits and small scripts in languages that I want to dig in to deeper so I know the basics and I don't want to waste any time on going trough stuff that I already know. So my question is: Is there any online course platform that will provide me fast paced almost bootcamp like course for advance developer that just want to learn coding in new language or for new platform?