The JetBrains Blog
ECMAScript 6 in WebStorm: Transpiling
WebStorm supports ECMAScript 6 syntax. This support actually includes not only the ECMAScript 2015 standard, but also the 2016, 2017, and 2018 standards and even some proposals to the language, for example, import(). While these features get more and more support in modern browsers and runtimes (see the Kangax compatibility table), to deploy your ES6 code you still often need to compile it to ES5.