From 21739b446dd7d5105dabb67adfff0937cbe06162 Mon Sep 17 00:00:00 2001
From: Eunjae Lee <eunjae.lee@algolia.com>
Date: Mon, 12 Oct 2020 14:33:26 +0200
Subject: [PATCH] feat(onStateChange): provide prevState (#335)

---
 packages/autocomplete-core/src/createStore.ts |  3 ++-
 packages/autocomplete-core/src/types/api.ts   | 10 ++++++++--
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/packages/autocomplete-core/src/createStore.ts b/packages/autocomplete-core/src/createStore.ts
index e2330b161..f09d6415c 100644
--- a/packages/autocomplete-core/src/createStore.ts
+++ b/packages/autocomplete-core/src/createStore.ts
@@ -25,6 +25,7 @@ export function createStore<TItem>(
       return state;
     },
     send(action, payload) {
+      const prevState = { ...state };
       state = enhanceState(
         reducer(state, {
           type: action,
@@ -33,7 +34,7 @@ export function createStore<TItem>(
         })
       );
 
-      props.onStateChange({ state });
+      props.onStateChange({ state, prevState });
     },
   };
 }
diff --git a/packages/autocomplete-core/src/types/api.ts b/packages/autocomplete-core/src/types/api.ts
index 2dd98d828..487e7876d 100644
--- a/packages/autocomplete-core/src/types/api.ts
+++ b/packages/autocomplete-core/src/types/api.ts
@@ -198,7 +198,10 @@ export interface AutocompleteOptions<TItem> {
   /**
    * Function called when the internal state changes.
    */
-  onStateChange?<TItem>(props: { state: AutocompleteState<TItem> }): void;
+  onStateChange?<TItem>(props: {
+    state: AutocompleteState<TItem>;
+    prevState: AutocompleteState<TItem>;
+  }): void;
   /**
    * The text that appears in the search box input when there is no query.
    */
@@ -282,7 +285,10 @@ export interface InternalAutocompleteOptions<TItem>
   extends AutocompleteOptions<TItem> {
   debug: boolean;
   id: string;
-  onStateChange<TItem>(props: { state: AutocompleteState<TItem> }): void;
+  onStateChange<TItem>(props: {
+    state: AutocompleteState<TItem>;
+    prevState: AutocompleteState<TItem>;
+  }): void;
   placeholder: string;
   autoFocus: boolean;
   defaultHighlightedIndex: number | null;