reactjs - React 不会在状态改变时重新渲染

Question

单击按钮时我正在渲染一个新表单。所以基本上我改变了组件内的状态:

从假到真或空到真

但是，奇怪的是，状态改变后组件没有重新渲染

export default class BoardManager extends React.Component{
   constructor(){
    super();
    this.state = {
      newForm : null
    };
    setTimeout(() => {
      this.state = {
        newForm : true
      };
      console.log(this.state.newForm);
    },1000);
  }

  render(){
    return(
      <div>
        Some thing here
        {this.state.newForm ? <NewBoardForm />: null}
      </div>
    )
  }
} 

非常感谢帮助!!!

编辑!解决方案

export default class BoardManager extends React.Component{
  constructor(){
    super();
    this.state = {
      newForm : null
    };
  }

  render(){
    return(
      <div>
        <BoardsTable boards={BoardData.boards}/>
        <button onClick={() => {
            this.setState({
              newForm : true
            });
            console.log(this.state.newForm);
          }}>Add New</button>
          <button onClick={() => {
              this.setState({
                newForm : null
              });
              console.log(this.state.newForm);
            }}>Delete</button>
        {this.state.newForm ? <NewBoardForm />: null}
      </div>
    )
  }
}

Answer 1

将 setTimeout 调用移至 componentDidMount 内部，并在其中使用 this.setState