Laravel Mix not transpiling vendor.js to es5

问题:

Laravel Mix does not seem to transpile vendor.js and manifest.js to ES5. It fails on iPhone Safari and IE 11.

IE DevTools shows these errors:

And it appears that it still has ES6 features:

The other files seem to transpile such as app.js and the chunks.

Here's my webpack.mix.js

let mix = require('laravel-mix');

let options = {
  processCssUrls: false,
}

let config = {
  output: {
    chunkFilename: 'assets/js/chunks/[name].js',
    publicPath: '/'
  }
}

if (mix.inProduction()) {
  config.output.chunkFilename = 'assets/js/chunks/[name].[chunkhash].js'
}

mix
  .js('resources/assets/js/app.js', 'public/assets/js')

  .sass('resources/assets/sass/web.scss', 'public/assets/css')
  .sass('resources/assets/sass/fonts.scss', 'public/assets/css')

  .copy('resources/assets/img', 'public/assets/img')
  .copy('node_modules/@fortawesome/fontawesome-free/webfonts','public/assets/webfonts')

  .extract([
      // Libraries...
  ])

  .disableNotifications()
  .webpackConfig(config)
  .options(options)
  .sourceMaps()

if (mix.inProduction()) {
  mix.version()
}

And my .babelrc

{
  "plugins": ["syntax-dynamic-import"]
}

I tried the following:

1. Install babel-preset-es2015 and add es2015 to my .babelrc presets.
2. Add .babel('[...]/vendor.js', '[...]/vendor.es5.js') to my webpack.mix.js

How can I get the vendor.js and manifest.js file to transpile to ES5? Or at least get it working with IE 11 and iPhone Safari.