ECMAScript 2018 was released in June 2018, adds fewer features than major editions (ES2016, ES2017) used to. These new changes are Asynchronous Iteration, Rest/Spread Properties, new features to Regular Expressions and a revision to template literals.
With synchronous iteratinos, we are able to iterate data from a synchronous source, but not when data is from an asynchronous source, for example https fetch.
We will recap synchronous iteration and then asynchronous iteration.