PostForm.tsx

const INITIAL_STATE: State = {
  name: '',
  content: '',
  isPosting: false,
  pendingPost: null,
  paymentRequest: null,
  error: null,
};

export default class PostForm extends React.Component<Props, State> {
  state = { ...INITIAL_STATE };

  componentDidUpdate() {
    const { posts } = this.props;
    const { pendingPost } = this.state;

    // Reset the form if our pending post comes in
    if (pendingPost) {
      const hasPosted = !!posts.find(p => pendingPost.id === p.id);
      if (hasPosted) {
        this.setState({ ...INITIAL_STATE });
      }
    }
  }

  /* ... */
}