Babel polyfill includes all polyfills no matter which targets are set - babeljs

Question

I am using Babel 7.1 together with rollup (v0.67). This is my rollup config:
{
input: 'src/svg.js',
output: {
file: 'dist/myBundle.js',
name: 'myBundle',
sourceMap: true,
format: 'iife'
},
plugins: [
resolve({browser: true}),
commonjs(),
babel({
include: 'src/**',
runtimeHelpers: true,
babelrc: false,
presets: [["#babel/preset-env", {
modules: false,
targets: {
firefox: "63"
},
useBuiltIns: "usage"
}]],
plugins: [["#babel/plugin-transform-runtime", {
corejs: false,
helpers: true,
regenerator: true,
useESModules: true
}]]
})
]
}
I want to polyfill older browsers. According to the docs, I need to include babel-polyfill in my entry point which I did. Now babel should include only the polyfills needed (because of useBuiltIns: "usage"). However, even when specifying the newest Browsers as target, I get the full load of code into my bundle (10000 lines of code).
What I tried:
I tried useBuiltIns: "entry" which fixes it for newer browsers but its not what I want (it just includes all polyfills which are potentially needed by the browser no matter if they are actually used in the code).
change the order of the rollup plugins
not include the babel-polyfill import
I have no idea why this is happening. It would be great if someone could solve this issue. Its driving me crazy!
And if someone knows as a bonus why no sourcemap is generated I dont mind getting an answer for that, too

Answer 1

Hey I made a repo which explores a good babel/rollup setup utilising preset-env and useBuiltIns 'usage'.
// Rollup plugins
import babel from 'rollup-plugin-babel';
import commonjs from 'rollup-plugin-commonjs';
import resolve from 'rollup-plugin-node-resolve';
export default {
input : 'main.js',
output : {
file : 'app.js',
format : 'iife',
name : 'PROJECT'
},
plugins : [
resolve(),
babel({
exclude : 'node_modules/**',
presets : [[
'#babel/env', {
useBuiltIns : 'usage'
}
]],
plugins : [
'#babel/plugin-transform-runtime'
],
runtimeHelpers : true
}),
commonjs()
]
};
Take a look https://github.com/matt3224/rollup-babel7
If you can figure out how to reduce the output further submit a PR