To take a look at some Javascript syntax, take a look here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript
To familiar yourself with ES6 syntax, which is the version of Javascript we will be using, make sure to look through this (especially sections 1-4): http://stack.formidable.com/es6-interactive-guide/#/
Also, understand....
that javascript classes are just functions
how to use string interpolation
arrow functions
More resources for Javascript and ES6: