Quick references for fundamental things in JavaScript.

👉 Reading: You Don't Know JS Yet 1 - Get Started

Miscellaneous

Practice directly on the browser

Open the browser (I use Chrome), press F12 to open the Inspect window, then choose tab Console. Now, you can practice on this console window, for example, try with 1+1 and press Ent.

ES6

Concise things

// Concise Object Literal Declarations
const getMousePosition = (x, y) => ({ x, y });