React: Props are immutable!

app.jsx

const News = props => {
  const changeTitle = () => {
    // Since props are read-only, you are not allowed to do so
    props.changeTitle("Title changed!");
  };
  return (
    <div>
      <h1>{props.title}</h1>
      <div>{props.content}</div>
      <button onClick={changeTitle}>Mutate!</button>
    </div>
  );
};

class App extends Component {
   ...
   <News title={title} content={content} changeTitle={this.changeTitle} />
   ...
}