Vue-loader does not recognize es2015 syntax - ecmascript-6

Question

I'm having an issue with vue-loader where it will not recognize es2015 format.
Here are the steps I'm taking:
//initialize the project via vue-cli
vue init webpack-simple && npm i
// start the webpack-dev-server, this npm script is an alias for the command:
// webpack-dev-server --inline --hot
npm run dev
At this point the files are being hosted by webpack-dev-server at localhost:8080 successfully.
When I modify App.vue and add anything es2015 in I get an error from webpack-dev-server:
<template>
<div id="app">
<h1>{{ msg }}</h1>
</div>
</template>
<script>
export default {
data () {
return {
msg: 'Hello Vue!'
}
},
// added this function call for the ready lifecycle hook
ready () => alert('worked')
}
</script>
<style>
body {
font-family: Helvetica, sans-serif;
}
</style>
This made me think that the es2015 preset for babel wasn't installed, but it is definitely in the dev dependencies list along with the transform-runtime:
// truncated package.json
{
...
"scripts": {
"dev": "webpack-dev-server --inline --hot",
"build": "cross-env NODE_ENV=production webpack --progress --hide-modules"
},
"dependencies": {
"vue": "^1.0.0",
"babel-runtime": "^5.8.0"
},
"devDependencies": {
"babel-core": "^6.0.0",
"babel-loader": "^6.0.0",
"babel-plugin-transform-runtime": "^6.0.0",
"babel-preset-es2015": "^6.0.0",
"babel-preset-stage-2": "^6.0.0",
"cross-env": "^1.0.6",
"css-loader": "^0.23.0",
"file-loader": "^0.8.4",
"json-loader": "^0.5.4",
"url-loader": "^0.5.7",
"vue-hot-reload-api": "^1.2.0",
"vue-html-loader": "^1.0.0",
"vue-loader": "^8.2.1",
"vue-style-loader": "^1.0.0",
"webpack": "^1.12.2",
"webpack-dev-server": "^1.12.0"
}
}
Plus the docs for vue-loader say that es2015 is enabled by default:
There are many cool features provided by vue-loader:
ES2015 enabled by default;
Is there a step or a configuration I'm missing?
Versions:
vue-cli: 2.0.3
npm: 3.8.6
node: 6.0.0

Answer 1

I think it should be
ready: () => alert('worked')
or
ready(){alert('worked')}