destructuring-mixed-scope-declarations-and-locals.js — react Source File

Source Code

import {useFragment} from 'shared-runtime';

function Component(props) {
  const post = useFragment(
    graphql`
      fragment F on T {
        id
      }
    `,
    props.post
  );
  const allUrls = [];
  // `media` and `urls` are exported from the scope that will wrap this code,
  // but `comments` is not (it doesn't need to be memoized, bc the callback
  // only checks `comments.length`)
  // because of the scope, the let declaration for media and urls are lifted
  // out of the scope, and the destructure statement ends up turning into
  // a reassignment, instead of a const declaration. this means we try to
  // reassign `comments` when there's no declaration for it.
  const {media, comments, urls} = post;
  const onClick = e => {
    if (!comments.length) {
      return;
    }
    console.log(comments.length);
  };
  allUrls.push(...urls);
  return <Media media={media} onClick={onClick} />;
}