Hello! Just in time for 7DRL, Roguelike Browser Boilerplate is now open source.
The boilerplate is a JavaScript based game template that takes care of all the annoying stuff like splash screen, start screen, credits screen, instructions screen, settings screen, menus, pixel styled UI, win/lose condition screens, sound effects, animations, etc. so you can get on with making the actual game.
It's ROT.js based and includes example implementations for monster, inventory, level gen, etc. It works on mobile and desktop.
The license is MIT so you can do what you want basically, including using it in a commercial game.
Enjoy!