State can get initial value from parent Component? about react-guide

[NiGhTTraX]

Even more, here it's stated that in the majority of simple cases having props in getInitialState is an anti-pattern.

It's an anti-pattern because if you set initial state using props, then you might have to resync it when new props come in. This is an indication that the props are the source of truth and that your component shouldn't hold state.

class C extends React.Component {
  constructor(props) {
    this.state = {
      foo: this.props.foo
    };
  }
  render() {
    return <div>{this.state.foo}</div>;
  }
}

ReactDOM.render(<C foo="bar" />, container);
ReactDOM.render(<C foo="baz" />, container);

The problem with the above is that you will probably expect "baz" to be rendered, but instead you'll get "bar" because that's the current state of the component and it wasn't updated when new props came in.

To fix that you can implement the componentWillReceiveProps method:

class C extends React.Component {
  constructor(props) {
    this.state = {
      foo: this.props.foo
    };
  }
  render() {
    return <div>{this.state.foo}</div>;
  }
  componentWillReceiveProps(nextProps) {
    // This is a code smell. It's telling you that the props are more
    // important than the state and that you should lose one of them.
    this.setState({ foo: nextProps.foo });
  }
}

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[demns]

@NiGhTTraX Andrei, thank you for your answer. What I actually meant is that you cannot automatically assign state value in the child component from the parent, the thing that you can do with props (without additional steps, of course). It was a bit confusing for me, but now I can understand that having yes in the table doesn't necessarily mean that it is done by React :)