From 5d26c15dafc025b458971a1c3c29494aa62e5a63 Mon Sep 17 00:00:00 2001
From: David Luzar <luzar.david@gmail.com>
Date: Fri, 26 Mar 2021 17:12:32 +0100
Subject: [PATCH] fix: debounce.flush invokes func even if never queued before
 (#3326)

* fix: `debounce.flush` invokes func even if never queued before

* reset after debounced invocation

* account for fn throwing
---
 src/utils.ts | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/utils.ts b/src/utils.ts
index 22f86dc64..11959d5cf 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -123,17 +123,25 @@ export const debounce = <T extends any[]>(
   timeout: number,
 ) => {
   let handle = 0;
-  let lastArgs: T;
+  let lastArgs: T | null = null;
   const ret = (...args: T) => {
     lastArgs = args;
     clearTimeout(handle);
-    handle = window.setTimeout(() => fn(...args), timeout);
+    handle = window.setTimeout(() => {
+      lastArgs = null;
+      fn(...args);
+    }, timeout);
   };
   ret.flush = () => {
     clearTimeout(handle);
-    fn(...(lastArgs || []));
+    if (lastArgs) {
+      const _lastArgs = lastArgs;
+      lastArgs = null;
+      fn(..._lastArgs);
+    }
   };
   ret.cancel = () => {
+    lastArgs = null;
     clearTimeout(handle);
   };
   return ret;