This are my notes from Erick Hanchett interview to Eric Elliott, about different base things a JS Developer should know.
First thing, learn about closures.
Learn what callbacks are and how to do Async programming.
Learn how to use Object.assign
Lear map, reduce and filter and use them all the time, sometimes you might use forEach, but favor map instead. Also look into lodash.
Know a bit of ES6, specially destructuring, parameter defaults, rest parameters, spread (a lot)… you’ll be in the right track if you know a bit about that syntax.
Learn about prototypes.