Star rating

Renders a star rating component.

• Define a Star component. It renders each individual star with the appropriate appearance, based on the parent component's state.
• Define a StarRating component. Use the useState() hook to define the rating and selection state variables with the appropriate initial values.
• Create a method, hoverOver, that updates selected according to the provided event, using the .data-star-id attribute of the event's target or resets it to 0 if called with a null argument.
• Use Array.from() to create an array of 5 elements and Array.prototype.map() to create individual <Star> components.
• Handle the onMouseOver and onMouseLeave events of the wrapping element using hoverOver. Handle the onClick event using setRating.

.star {
  color: #ff9933;
  cursor: pointer;
}

const Star = ({ marked, starId }) => {
  return (
    <span data-star-id={starId} className="star" role="button">
      {marked ? '\u2605' : '\u2606'}
    </span>
  );
};

const StarRating = ({ value }) => {
  const [rating, setRating] = React.useState(parseInt(value) || 0);
  const [selection, setSelection] = React.useState(0);

  const hoverOver = event => {
    let val = 0;
    if (event && event.target && event.target.getAttribute('data-star-id'))
      val = event.target.getAttribute('data-star-id');
    setSelection(val);
  };
  return (
    <div
      onMouseOut={() => hoverOver(null)}
      onClick={e => setRating(e.target.getAttribute('data-star-id') || rating)}
      onMouseOver={hoverOver}
    >
      {Array.from({ length: 5 }, (v, i) => (
        <Star
          starId={i + 1}
          key={`star_${i + 1}`}
          marked={selection ? selection >= i + 1 : rating >= i + 1}
        />
      ))}
    </div>
  );
};

ReactDOM.render(<StarRating value={2} />, document.getElementById('root'));