The 2018 Web Developer : Adding and using babel

Babel is a JavaScript compiler. It allows you to use modern JavaScript, then compiles it to a file which will work in all browsers.
To install it, use :
npm install -g babel-cli
To run it, change to the directory containing your JavaScript:
cd myApp
Then run a command like this:
npx babel custom.js -w -o script.js
custom.js is the file you are editing ans script.js is your output file. If you are using the -w (watch) parameter as above, the compilation will take place each time you save custom.js.