How to setup a vue-cli with vuetify project to run with IE 11?

I'll do a partial answer.

1) @vue/app and babel presets are included in vue-cli.

https://cli.vuejs.org/guide/browser-compatibility.html#polyfills

This is stated clearly in the vue-cli documentation. But it also specifies:

"If one of your dependencies need polyfills, you have a few options:

If the dependency is written in an ES version that your target environments do not support: Add that dependency to the transpileDependencies option in vue.config.js"

2) You still need to put the babel polyfill in each entry file.

Traditionally: import '@babel/polyfill' in your main.ts.

What babel-preset-env does is that it detects your browserlist then replaces that line with whatever polyfills it deems necessary.

3) @babel/polyfill is deprecated. Who knew.

Some people need extra heavy duty polyfills. That's me. Because internet exploder in office-js + being too used to bleeding edge tech. That's where core-js @ 3 comes in.

My webpack build is fully custom for that purpose. But i ripped it out of the vue-cli and modified from there.

My babel loader config :

const BABEL_LOADER = {
    loader: 'babel-loader',
    options: {
        plugins: ['@babel/plugin-syntax-dynamic-import'],
        presets: [
            // '@vue/app',
            ['@babel/preset-env', {
                targets: {
                    ie: '11',
                    browsers: 'last 2 versions',
                },
                useBuiltIns: 'usage',
                corejs: { version: 3, proposals: true },
            }],
        ],
    },
};

This is the top of my entry file:

import Vue from 'vue';
import App from './App.vue';


// ------------ Polyfill ------------
import 'core-js/stable';

The core-js replaces @babel/polyfill.

More reading on core-js: https://github.com/zloirock/core-js/blob/master/docs/2019-03-19-core-js-3-babel-and-a-look-into-the-future.md