咱们大部分的use逻辑（包含useState、useCallback等等，所有的use）都是写在react-dom这个库里，然而ReactCurrentDispatcher的逻辑有一部分在react库里。

本篇次要梳理ReactCurrentDispatcher这个对象在整个react中的作用

在react库中，定义了全局变量：

/*** Keeps track of the current dispatcher.*/var ReactCurrentDispatcher = {/** * @internal * @type {ReactComponent} */  current: null};// ....很多行之后var ReactSharedInternals$1 = {    ReactCurrentDispatcher: ReactCurrentDispatcher,    ReactCurrentOwner: ReactCurrentOwner,    IsSomeRendererActing: IsSomeRendererActing,    ReactCurrentBatchConfig: ReactCurrentBatchConfig,    // Used by renderers to avoid bundling object-assign twice in UMD bundles:    assign: assign,    // Re-export the schedule API(s) for UMD bundles.    // This avoids introducing a dependency on a new UMD global in a minor update,    // Since that would be a breaking change (e.g. for all existing CodeSandboxes).    // This re-export is only required for UMD bundles;    // CJS bundles use the shared NPM package.    Scheduler: Scheduler,    SchedulerTracing: SchedulerTracing  };      // ...很多行之后  exports.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED = ReactSharedInternals$1;

在react-dom中，有这样的引入值：

var ReactSharedInternals = React.__SECRET_INTERNALS_DO_NOT_USE_OR_YOU_WILL_BE_FIRED;// ...很多行之后var ReactCurrentDispatcher = ReactSharedInternals.ReactCurrentDispatcher;// ...很多行之后var ReactCurrentDispatcher$1 = ReactSharedInternals.ReactCurrentDispatcher,    ReactCurrentBatchConfig$1 = ReactSharedInternals.ReactCurrentBatchConfig;

ReactCurrentDispatcher$1，其实就是一个对象。对象内只有一个key：current

ReactCurrentDispatcher的作用，其实就是用来保留以下对象的：
HooksDispatcherOnMountInDEV
HooksDispatcherOnMountWithHookTypesInDEV
HooksDispatcherOnUpdateInDEV
HooksDispatcherOnRerenderInDEV
InvalidNestedHooksDispatcherOnMountInDEV
InvalidNestedHooksDispatcherOnUpdateInDEV
InvalidNestedHooksDispatcherOnRerenderInDEV
而这些对象中，都实现残缺的一套use。
代码构造大略是这样：

ReactCurrentDispatcher = {  HooksDispatcherOnMountInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  HooksDispatcherOnMountWithHookTypesInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  HooksDispatcherOnUpdateInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  HooksDispatcherOnRerenderInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  InvalidNestedHooksDispatcherOnMountInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  InvalidNestedHooksDispatcherOnUpdateInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },  InvalidNestedHooksDispatcherOnRerenderInDEV: {    useState: function() {...},    useCallback: function() {...},    useEffect: function() {...},    ...其余use  },};

当然代码中对专用逻辑局部做了抽离，并没有冗余的逻辑和代码。
咱们会在这篇文章中阐明hooktype，也就是ReactCurrentDispatcher的实现逻辑：
react hooks外围：hooktype和ReactCurrentDispatcher