Not really next-gen JavaScript, but also important: JavaScript array functions like map() , filter() , reduce() etc. You’ll see me use them quite a bit since a lot of React concepts rely on working with arrays (in immutable ways). The following page gives a good overview of the various methods you can use on the array prototype — feel free to click through them and refresh your knowledge as required: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array map() => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map find() => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find findIndex() => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex filter() => https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Glo...