Ask HN: What are best resources for a Java developer to learn web programming?

I spent the first 7 years of my career as a Java developer, but I haven't seriously coded for almost a decade. I have an idea for a web product that I'd like to develop, and I'd like to get a beta version put together to feedback from prospective customers before I think about quitting my job to pursue it.<p>To that end, I need to get a handle on the various technologies used in web development (i.e. I need to do more than just learn JavaScript).<p>What are some good resources for getting started?