event registry

一、作用

二、导出的常量

1. 所有本地事件

备注

• enableCreateEventHandleAPI() 由 ReactFeatureFlags#enableCreateEventHandleAPI 提供

export const allNativeEvents: Set<DOMEventName> = new Set();
if (enableCreateEventHandleAPI) {
  allNativeEvents.add('beforeblur');
  allNativeEvents.add('afterblur');
}

2. 注册名称依赖

/**
 * Mapping from registration name to event name
 * 从注册名映射到事件名
 */
export const registrationNameDependencies: {
  [registrationName: string]: Array<DOMEventName>;
} = {};

3. 可能的注册名称

/**
 * Mapping from lowercase registration names to the properly cased version,
 * used to warn in the case of missing event handlers. Available
 * only in __DEV__.
 *
 * 从小写注册名称映射到正确的大小写版本，用于在缺少事件处理程序时发出警告。仅用在开发阶段
 *
 * @type {Object}
 */
export const possibleRegistrationNames: {
  [lowerCasedName: string]: string;
} = __DEV__ ? {} : (null as any);
// Trust the developer to only use possibleRegistrationNames in __DEV__
// 相信开发者只会在 __DEV__ 中使用 possibleRegistrationNames

三、注册两阶段事件

export function registerTwoPhaseEvent(
  registrationName: string,
  dependencies: Array<DOMEventName>,
): void {
  registerDirectEvent(registrationName, dependencies);
  registerDirectEvent(registrationName + 'Capture', dependencies);
}

四、注册直接事件

export function registerDirectEvent(
  registrationName: string,
  dependencies: Array<DOMEventName>,
) {
  if (__DEV__) {
    if (registrationNameDependencies[registrationName]) {
      console.error(
        'EventRegistry: More than one plugin attempted to publish the same ' +
          'registration name, `%s`.',
        registrationName,
      );
    }
  }

  registrationNameDependencies[registrationName] = dependencies;

  if (__DEV__) {
    const lowerCasedName = registrationName.toLowerCase();
    possibleRegistrationNames[lowerCasedName] = registrationName;

    if (registrationName === 'onDoubleClick') {
      possibleRegistrationNames.ondblclick = registrationName;
    }
  }

  for (let i = 0; i < dependencies.length; i++) {
    allNativeEvents.add(dependencies[i]);
  }
}