From ae12d948f10378016cf436f8e5890f70072181e6 Mon Sep 17 00:00:00 2001
From: Zebulan Stanphill <zebulanstanphill@protonmail.com>
Date: Wed, 13 Oct 2021 14:43:20 -0500
Subject: [PATCH] Convert usePrevious hook to TypeScript. (#35597)

---
 .../compose/src/hooks/use-previous/index.js   | 31 -------------------
 .../compose/src/hooks/use-previous/index.ts   | 24 ++++++++++++++
 2 files changed, 24 insertions(+), 31 deletions(-)
 delete mode 100644 packages/compose/src/hooks/use-previous/index.js
 create mode 100644 packages/compose/src/hooks/use-previous/index.ts

diff --git a/packages/compose/src/hooks/use-previous/index.js b/packages/compose/src/hooks/use-previous/index.js
deleted file mode 100644
index c50e392a43226..0000000000000
--- a/packages/compose/src/hooks/use-previous/index.js
+++ /dev/null
@@ -1,31 +0,0 @@
-/**
- * WordPress dependencies
- */
-import { useEffect, useRef } from '@wordpress/element';
-
-/**
- * Use something's value from the previous render.
- * Based on https://usehooks.com/usePrevious/.
- *
- * @template T
- *
- * @param {T} value The value to track.
- *
- * @return {T | undefined} The value from the previous render.
- */
-export default function usePrevious( value ) {
-	// Disable reason: without an explicit type detail, the type of ref will be
-	// inferred based on the initial useRef argument, which is undefined.
-	// https://github.com/WordPress/gutenberg/pull/22597#issuecomment-633588366
-	/* eslint-disable jsdoc/no-undefined-types */
-	const ref = useRef( /** @type {T | undefined} */ ( undefined ) );
-	/* eslint-enable jsdoc/no-undefined-types */
-
-	// Store current value in ref.
-	useEffect( () => {
-		ref.current = value;
-	}, [ value ] ); // Re-run when value changes.
-
-	// Return previous value (happens before update in useEffect above).
-	return ref.current;
-}
diff --git a/packages/compose/src/hooks/use-previous/index.ts b/packages/compose/src/hooks/use-previous/index.ts
new file mode 100644
index 0000000000000..cdc06c37f08fe
--- /dev/null
+++ b/packages/compose/src/hooks/use-previous/index.ts
@@ -0,0 +1,24 @@
+/**
+ * WordPress dependencies
+ */
+import { useEffect, useRef } from '@wordpress/element';
+
+/**
+ * Use something's value from the previous render.
+ * Based on https://usehooks.com/usePrevious/.
+ *
+ * @param  value The value to track.
+ *
+ * @return The value from the previous render.
+ */
+export default function usePrevious< T >( value: T ): T | undefined {
+	const ref = useRef< T >();
+
+	// Store current value in ref.
+	useEffect( () => {
+		ref.current = value;
+	}, [ value ] ); // Re-run when value changes.
+
+	// Return previous value (happens before update in useEffect above).
+	return ref.current;
+}