If you need to specify initial state in a class, I see people did this

class App extends React.Component {
   constructor() { super(); this.state = { user: [] } }
   render() {
      return <p>Hi</p>
   }
}

but what's wrong without a constructor?

class App extends React.Component {
   state = { user: [] }
   render() {
      return <p>Hi</p>
   }
}

If you need to specify initial state in a class, I see people did this

class App extends React.Component {
   constructor() { super(); this.state = { user: [] } }
   render() {
      return <p>Hi</p>
   }
}

but what's wrong without a constructor?

class App extends React.Component {
   state = { user: [] }
   render() {
      return <p>Hi</p>
   }
}

• javascript
• reactjs
• ecmascript-6

1 Answer 1

but what's wrong without a constructor?

There is nothing "wrong" with it. But it uses the class properties proposal which is not officially part of the language yet (since you tagged the question with ecmascript-6: It is not part of ES6). So you have to correctly configure your build system to be able to use it (in addition to what's needed for JSX).