Type safety for dispatch signature

reduxjs · Mar 17, 2016 · 74e16aa · 74e16aa
1 parent 175f32a
commit 74e16aa
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Showing 2 changed files with 9 additions and 3 deletions.
diff --git a/index.d.ts b/index.d.ts
@@ -75,6 +75,10 @@ export function combineReducers<S>(reducers: ReducersMapObject): Reducer<S>;
 
 /* store */
 
+export interface MiddlewareDispatch {
+    <TMiddlewareAction, TMiddlewareActionResult>(action: TMiddlewareAction): TMiddlewareActionResult;
+}
+
 /**
  * A *dispatching function* (or simply *dispatch function*) is a function that
  * accepts an action or an async action; it then may or may not dispatch one
@@ -93,7 +97,9 @@ export function combineReducers<S>(reducers: ReducersMapObject): Reducer<S>;
  * transform, delay, ignore, or otherwise interpret actions or async actions
  * before passing them to the next middleware.
  */
-export type Dispatch = (action: any) => any;
+export interface Dispatch extends MiddlewareDispatch {
+    (action: Action): Action;
+}
 
 /**
  * Function to remove listener added by `Store.subscribe()`.
@@ -265,7 +271,7 @@ export interface MiddlewareAPI<S> {
  * asynchronous API call into a series of synchronous actions.
  */
 export interface Middleware {
-  <S>(api: MiddlewareAPI<S>): (next: Dispatch) => (action: any) => any;
+  <S>(api: MiddlewareAPI<S>): (next: MiddlewareDispatch) => MiddlewareDispatch;
 }
 
 /**

diff --git a/test/typescript/dispatch.ts b/test/typescript/dispatch.ts
@@ -9,4 +9,4 @@ const dispatchResult: Action = dispatch({type: 'TYPE'});
 
 type Thunk<O> = () => O;
 
-const dispatchThunkResult: number = dispatch(() => 42);
+const dispatchThunkResult: number = dispatch<Thunk<number>, number>(() => 42);