This default settings for babel-loader in Vuepack:
{
babelrc: false,
presets: [
['es2015', {modules: false}],
'stage-1'
],
plugins: [
'transform-vue-jsx'
]
}
Which means you can use all ES2015 and ESnext stage-1 features, and Vue JSX support.
You can update it in ./build/config.js.