Socket.io 事件侦听器在我的 React 类组件中自发触发，没有服务器输出

Question

I'm trying to implement some socket.io code in my React class component, but it doesn't seem to be working properly. My code looks like this:

class foo extends React.Component {
  constructor(props) {
    super(props)
    this.state = {
      socket: io("localhost:5000")
    }
  }
  componentDidMount() {
    this.state.socket.on("event", console.log("event logged."))
  }
  render() {
    return (
      <div>
        <h1>Hello World!</h1>
      </div>
    )
  }
}

When I load up the React page in Chrome and open the dev tools console, I immediately see a "event logged." message. Any ideas on why this is happening? No server is running, so I'm confused as to why the socket event is triggered.

Thanks in advance for any feedback.

Answer 1

you have to pass a function as second argument to socket.on ,

componentDidMount() {
    this.state.socket.on("event", (data) => {console.log("event logged.")});
  }