JavaScript for Beginners: Make a Web Page Actually Do Something

This is for people who have never written JavaScript and want a web page that reacts when someone clicks, types or submits. You will write JavaScript that runs in your browser, change the page with it, and read your own errors instead of pasting code you don't understand. If you skip the basics and copy snippets until something works, you will be stuck the first time the console turns red, and it will turn red.