在React组件安装到DOM后触发了任何事件吗？

Question

If I try to do document.querySelector for an element inside the React component inside componentDidMount , it seems like it does not guarantee it ( componentDidMount ) gets called after its on the DOM. The result is it cannot find the element

Is there an event I should used instead if I want to access the DOM? After its attached to the DOM?

As a workaround, I used setTimeout is there a better way?

Answer 1

Another approach is that in your componentDidMount method set some state change. it makes an update on your component and call render method again with absolute mounted status.

like this:

componentDidMount(){
  this.setState({
    isMounted: true
  })
}

componentWillUpdate(nextProps, nextState){
  if(nextState.isMounted){
     // do something for your query selecting
  }
}

componentWillUnmount(){
  // do something else if you want
}