https://eloquentjavascript.net/
https://developer.mozilla.org/en-US/docs/Learn/Getting_started_with_the_web/JavaScript_basics
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String https://developer.mozilla.org/en-US/docs/Learn/JavaScript/First_steps/Useful_string_methods
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math https://www.tutorialspoint.com/javascript/javascript_math_object.htm
