componentDidUpdate(prevProps, prevState){
  if (prevProps.match.params.vendor !== this.props.match.params.vendor &&
      this.props.myArray.length > 1){
    this.props.myDispatchedAction();
  }
}

useEffect(() => {
    if (myArray.length > 1){
      myDispatchedAction();
    }
}, [match.params.vendor, myDispatchedAction, myArray]);