Read Exploring ES6 by Axel Rauschmayer for free http://exploringjs.com/es6/
JavaScript Allongé, the "Six" Edition - read it for free at Leanpub (where you can also buy it) https://leanpub.com/javascriptallongesix/read
Creating a simple GTK+ to-do application with Ruby - iridakos https://iridakos.com/tutorials/2018/01/25/creating-a-gtk-todo-application-with-ruby