Optional
Called immediately before mounting occurs, and before Component.render. Avoid introducing any side-effects or subscriptions in this method.
This method will not stop working in React 17.
Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.
16.3, use componentDidMount or the constructor instead
Called immediately before mounting occurs, and before Component.render. Avoid introducing any side-effects or subscriptions in this method.
This method will not stop working in React 17.
Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.