mutation-within-capture-and-mutablerange.tsx — react Source File

Source Code

import {mutate} from 'shared-runtime';

/**
 * This test fixture is similar to mutation-within-jsx. The only difference
 * is that there is no `freeze` effect here, which means that `z` may be
 * mutated after its memo block through mutating `y`.
 *
 * While this is technically correct (as `z` is a nested memo block), it
 * is an edge case as we believe that values are not mutated after their
 * memo blocks (which may lead to 'tearing', i.e. mutating one render's
 * values in a subsequent render.
 */
function useFoo({a, b}) {
  // x and y's scopes start here
  const x = {a};
  const y = [b];
  mutate(x);
  // z captures the result of `mutate(y)`, which may be aliased to `y`.
  const z = [mutate(y)];
  // the following line may also mutate z
  mutate(y);
  // and end here
  return z;
}

export const FIXTURE_ENTRYPOINT = {
  fn: useFoo,
  params: [{a: 2, b: 3}],
};