Typescript incorporated a lot of features from ES6 with its very useful syntax sugar what can make the code more concise and expressive. Main ES6 features we are currently using are: * destructuring, spread and rest * async/await * arrow functions * const, let * classes (but still following more functional approach) * default values * string interpolation

We think that it's extremely important that developers learn and become experts in ES6, as it has a lot of new syntax structures which have hidden edge cases and this might sometimes create unexpected bugs in the system. Good example of such bugs can be default values which are not replacing falsy values (what || would do), but it only provides a default when the value is undefined.