<!-- IMPORTANT: Please use the following link to create a new issue: https://new-issue.vuejs.org/?repo=vuejs/vue-cli If your issue was not created using the app above, it will be closed immediately. 中文用户请注意: 请使用上面的链接来创建新的 issue。如果不是用上述工具创建的 issue 会被自动关闭。 --> I use `vue-cli 3.0.0-alpha.7` to create a new default project as below: <img width="884" alt="wx20180204-162311 2x" src="https://user-images.githubusercontent.com/8834733/35775664-0d5ccc36-09c8-11e8-8741-aed0a576dced.png"> Than I add `socket.io-client` by using ``` yarn add socket.io-client ``` and use it in `App.vue` as below: ```javascript <script> import HelloWorld from './components/HelloWorld.vue' import io from 'socket.io-client' export default { name: 'app', components: { HelloWorld }, created() { const socket = io('/home') socket.on('hello world', (hello) => { console.log('hello: ', hello) }) }, } </script> ``` However, I got an error about `Uncaught ReferenceError: global is not defined` <img width="541" alt="screen shot 2018-02-04 at 4 28 22 pm" src="https://user-images.githubusercontent.com/8834733/35775675-7bc80f0a-09c8-11e8-8f8b-b72a6d1e5ebd.png"> This seems not the bug of `socket.io-client` since I have no error in the project generated by legacy vue-cli 2.