Ask HN: What web technologies should I learn before entering the field?

I haven't done web development in 5+ years and am anticipating re-entering the field shortly. This could mean writing any web site from e-commerce, to basic company landing pages, to a complex javascript/html5 app, etc.<p>I assume I'll need to know jQuery for client side stuff, and I've heard Node.js is really useful. But what other frameworks are gaining traction today that are worth knowing? It seems like there are so many frameworks, each with different advantages/disadvantages that I have a hard time figuring out where to start!