Keeping up with the changes brought to the language is a must. Fortunately, updates are only to be expected annually, and you can track the upcoming ones on the github for tc39.
A Beginner’s Guide to Async/Await in JavaScript on itnext.io
Async functions - making promises friendly on developers.google.com
JavaScript Visualized: Generators and Iterators on dev.to
JavaScript is a dynamically-typed (or loosely-typed) language. Which means a variable could point to a variable with a given data type and then to a value of another data type. There is no mechanism enforcing that a function returns a value from a specific data type.
TypeScript aims to fix this, by bringing type safety to JavaScript. TypeScript code transpiles into JavaScript to be used in the same environments where you used JavaScript.