react-native/Libraries/Components/StaticContainer.react.js

/**
 * 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.
 *
 * @format
 * @flow strict-local
 */

'use strict';

const React = require('react');

/**
 * Renders static content efficiently by allowing React to short-circuit the
 * reconciliation process. This component should be used when you know that a
 * subtree of components will never need to be updated.
 *
 *   const someValue = ...; // We know for certain this value will never change.
 *   return (
 *     <StaticContainer>
 *       <MyComponent value={someValue} />
 *     </StaticContainer>
 *   );
 *
 * Typically, you will not need to use this component and should opt for normal
 * React reconciliation.
 */

type Props = $ReadOnly<{|
  /**
   * Whether or not this component should update.
   */
  shouldUpdate: ?boolean,
  /**
   * Content short-circuited by React reconciliation process.
   */
  children: React.Node,
|}>;
class StaticContainer extends React.Component<Props> {
  shouldComponentUpdate(nextProps: Props): boolean {
    return !!nextProps.shouldUpdate;
  }

  render(): null | React$Node {
    const child = this.props.children;
    return child === null || child === false
      ? null
      : React.Children.only(child);
  }
}

module.exports = StaticContainer;