How expose a exported function into global scope with babel and webpack

check out: https://github.com/webpack/docs/wiki/library-and-externals#examples

By setting the library output property to whatever name you want to wrap your globals would allow you to then call: YourLibrary.test();

module.exports = {
    entry: ['./_js/script.js'],
    output: {
       library: 'YourLibrary',
        path: __dirname,
        filename: './build/script.js'
    }

You can easily set a property on the global window object. This will expose your object to the global scope.

function test() {
  console.log('test');
}

window.test = test;

If you are developing a piece of code that does not represent a library but just some operations or functionalities to operate in global scope, I would prefer this method over to setting the library output property as mentioned in the accepted answer.