Understanding TypeScript with React

What happens when a React component receives a prop of the wrong type? In plain JavaScript, usually nothing visible happens at first. This ProfileCard expects a number for age, and a caller passes text:

const ProfileCard = ({ name, age }) => {
  return (
    <p>
      {name} is {age} years old
    </p>
  );
};

const page = <ProfileCard name="Ana" age="thirty" />;

The component renders "Ana is thirty years old", and no tool reports a problem. The fault appears later, perhaps when other code tries to calculate with age