react-esm/dist-src/ReactCreateRef.js

React is a JavaScript library for building user interfaces.

/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 * 
 */
// an immutable object with a single mutable value
export function createRef() {
  const refObject = {
    current: null
  };

  if (__DEV__) {
    Object.seal(refObject);
  }

  return refObject;
}