Implement extra arguments functionality

Author: lkmill

README.md

@@ -191,6 +191,7 @@ Creates a new store, which is a tiny evented state container.
 **Parameters**
 
 - `state` **[Object](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object)** Optional initial state (optional, default `{}`)
+- `extraArgs`  
 
 **Examples**
 

index.d.ts

@@ -20,7 +20,7 @@ export interface Store<K> {
 	getState(): K;
 }
 
-export default function createStore<K>(state?: K): Store<K>;
+export default function createStore<K>(state?: K, extraArgs?: any[] | any): Store<K>;
 
 export interface ActionMap<K> {
 	[actionName: string]: ActionCreator<K>;

src/index.js

@@ -11,7 +11,7 @@ import { assign } from './util';
  * store.setState({ a: 'b' });   // logs { a: 'b' }
  * store.setState({ c: 'd' });   // logs { a: 'b', c: 'd' }
  */
-export default function createStore(state) {
+export default function createStore(state, extraArgs) {
 	let listeners = [];
 	state = state || {};
 
@@ -52,7 +52,8 @@ export default function createStore(state) {
 			function apply(result) {
 				setState(result, false, action);
 			}
-			let ret = (action.action || action)(state, this);
+			let args = [state, this];
+			let ret = (action.action || action).apply(null, extraArgs ? args.concat(extraArgs) : args);
 			if (ret != null) {
 				if (ret.then) return ret.then(apply);
 				return apply(ret);