Hi there.
Hoping someone can assist me here 
I’m pretty new to using module bundlers in client side js code.
I asked on github about using the IE polyfils for stimulus, without needed to go all-in with webpack - the responses were helpful - and rollup.js looked like a nice solution to allow me to use stimulus properly in my web app, without having to totally switch to webpack.
I can get things working with rollupjs - here’s my “entry point” for example:
import { Application } from "stimulus"
import HelloController from "../controllers/hello_controller"
StimulusDelegates();
const application = Application.start();
application.register("hello", HelloController);
I’ve got a gulp task to deal with this, that calls rollup:
const rollupJS = (inputFile, options) => {
return () => {
return rollup({
input: options.basePath + inputFile,
format: options.format,
sourcemap: options.sourcemap,
plugins: [rollupResolve()]
})
// point to the entry file.
.pipe(source(inputFile, options.basePath))
// we need to buffer the output, since many gulp plugins don't support streams.
.pipe(buffer())
.pipe(sourcemaps.init({loadMaps: true}))
.pipe(babel({
presets: [['@babel/preset-env', {modules: false}]],
plugins: ['@babel/plugin-proposal-class-properties']
}))
.pipe(sourcemaps.write('.'))
.pipe(gulp.dest(options.distPath));
};
}
All that seems to be working, and gives me a nice file that seems to work on most browsers, apart from IE11 
So - I npm install the @stimulus/polyfills, and add this to the start of my entry point JS file:
import "@stimulus/polyfills"
But when I rollup that file now, and try to run it, I get an error:
Uncaught ReferenceError: require is not defined
at find.js:1
at UserListingStimulus.js? [sm]:1
And sure enough, when I look at the JS rollup has generated, it’s peppered with “require” statements - which obviously aint gonna work - here’s a snippet of the generated code:
require('../../modules/es6.array.find');
module.exports = require('../../modules/_core').Array.find;
require('../../modules/es6.array.find-index');
Does anyone know what’s going on here, or what I can do to sort it out?! Things were looking so good with rollup 'till now !