javascript - react.js constructor called twice

Question

I a have post list and I am trying to call an action inside of constructor or componentDidMount for each post. But somehow when I send a new message constructor and componentDidMount functions are called twice.

 constructor(props) {
    super(props);

    if (condition1) {
       this.props.actions.action1();
    } else if (condition2) {
       this.props.actions.action2();
    }    
}

These functions are called only once when the posts are readed from a list. But when I send a new message they are called twice.

How can i avoid these situation. I tried to use componendDidUpdate function like this:

componentDidUpdate(prevProps, prevState) {     
      if (prevProps.post.id !== this.props.post.id) {
         if (condition1) {
            this.props.actions.action1();
         } else if (condition2) {
            this.props.actions.action2();
         }
      }   
}

Answer 1

React constructor is called twice in strict mode. https://stackoverflow.com/a/61443443/6014725

This is not a bug, but on purpose behavior to ensure that the constructor is pure. https://github.com/facebook/react/issues/12856#issuecomment-613145789

Learn more with https://reactjs.org/docs/strict-mode.html