The best alternatives to JsTips are JavaScript.com, WoofJS, and JavaScript Quiz. If these 3 options don't work for you, we've listed a few more alternatives below.
Joshua Comeau has made this really useful list of JavaScript operators and presented it in a really good way. I've learned a lot, and hope you learn too.
Ultra is a fast and efficient package manager for JavaScript, it uses a shared store to install packages faster and save space on common dependencies shared by your projects. Also it comes with some commands like "create" to initialize template projects.