Configuration for our beloved frontend tools is hot lava. Today CLI tools as create-react-app or Vue cli abstract away most of the configuration, other than providing sane defaults.

Even then, understanding how things work under the hood is beneficial because sooner or later you'll need to make some adjustment to the defaults.

In this post we're going to see how babel preset-env, core-js, and browserslistrc work nicely together to enable newer JavaScript features for older browsers.