From 27e4444dd3740cc60e642c04e3226313dad9bc3a Mon Sep 17 00:00:00 2001
From: Luis Felipe Zaguini <luisfelipezaguini@gmail.com>
Date: Thu, 21 Mar 2019 10:07:41 -0300
Subject: [PATCH 1/5] Create useUpdateEffect.ts

---
 src/useUpdateEffect.ts | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 src/useUpdateEffect.ts

diff --git a/src/useUpdateEffect.ts b/src/useUpdateEffect.ts
new file mode 100644
index 0000000000..e696b034fb
--- /dev/null
+++ b/src/useUpdateEffect.ts
@@ -0,0 +1,16 @@
+import { useRef, useEffect } from 'react'
+
+const useUpdateEffect: typeof useEffect = (effect, deps) => {
+  const isInitialMount = useRef(true)
+
+  useEffect(
+    isInitialMount.current
+      ? () => {
+          isInitialMount.current = false
+        }
+      : effect,
+    deps
+  )
+}
+
+export default useUpdateEffect

From 7ca74e6aad424a10a9147d27aebdfe5ac0175412 Mon Sep 17 00:00:00 2001
From: Luis Felipe Zaguini <luisfelipezaguini@gmail.com>
Date: Thu, 21 Mar 2019 10:12:01 -0300
Subject: [PATCH 2/5] Create useUpdateEffect.md

---
 docs/useUpdateEffect.md | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 docs/useUpdateEffect.md

diff --git a/docs/useUpdateEffect.md b/docs/useUpdateEffect.md
new file mode 100644
index 0000000000..ca3c7f6d75
--- /dev/null
+++ b/docs/useUpdateEffect.md
@@ -0,0 +1,35 @@
+# `useUpdateEffect`
+
+React effect hook that ignores the first invocation (e.g. on mount). The signature is exactly the same as the `useEffect` hook.
+
+
+## Usage
+
+```jsx
+import React from 'react'
+import {useUpdateEffect} from 'react-use';
+
+const Demo = () => {
+  const [count, setCount] = React.useState(0);
+  
+  React.useEffect(() => {
+    const interval = setInterval(() => {
+      setCount(count => count + 1)
+    }, 1000)
+    
+    return () => {
+      clearInterval(interval)
+    }
+  }, [])
+  
+  useUpdateEffect(() => {
+    console.log('count', count) // will only show 1 and beyond
+    
+    return () => { // *OPTIONAL*
+      // do something on unmount
+    }
+  }) // you can include deps array if necessary
+
+  return <div>Count: {count}</div>
+};
+```

From d7f9ee4cb388b3b15f9b2be2809c4d4012749676 Mon Sep 17 00:00:00 2001
From: Luis Felipe Zaguini <luisfelipezaguini@gmail.com>
Date: Thu, 21 Mar 2019 10:14:31 -0300
Subject: [PATCH 3/5] Update index.ts

---
 src/index.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/index.ts b/src/index.ts
index 66bdf580d9..6fb4a79f76 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -49,6 +49,7 @@ import useUpdate from './useUpdate';
 import useVideo from './useVideo';
 import useWindowSize from './useWindowSize';
 import useWait from './useWait';
+import useUpdateEffect from './useUpdateEffect'
 
 export {
   createMemo,
@@ -101,5 +102,6 @@ export {
   useUpdate,
   useVideo,
   useWindowSize,
-  useWait
+  useWait,
+  useUpdateEffect
 };

From 257d8c074a6ebb24beef5a3bf4bc54bfd6ec5565 Mon Sep 17 00:00:00 2001
From: Luis Felipe Zaguini <luisfelipezaguini@gmail.com>
Date: Thu, 21 Mar 2019 10:15:42 -0300
Subject: [PATCH 4/5] Update README.md

---
 README.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/README.md b/README.md
index 2e89bc68a1..8d2f0faab1 100644
--- a/README.md
+++ b/README.md
@@ -82,6 +82,7 @@
   - [`useLogger`](./docs/useLogger.md) &mdash; logs in console as component goes through life-cycles.
   - [`useMount`](./docs/useMount.md) &mdash; calls `mount` callbacks.
   - [`useUnmount`](./docs/useUnmount.md) &mdash; calls `unmount` callbacks.
+  - [`useUpdateEffect`](./docs/useUpdateEffect.md) &mdash; run an `effect` only on updates.
     <br/>
     <br/>
 - [**State**](./docs/State.md)

From 26953f12cf48a4793ebca1b34839c204b0f811b2 Mon Sep 17 00:00:00 2001
From: Luis Felipe Zaguini <luisfelipezaguini@gmail.com>
Date: Thu, 21 Mar 2019 10:20:36 -0300
Subject: [PATCH 5/5] Create useUpdateEffect.story.tsx

---
 src/__stories__/useUpdateEffect.story.tsx | 25 +++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 src/__stories__/useUpdateEffect.story.tsx

diff --git a/src/__stories__/useUpdateEffect.story.tsx b/src/__stories__/useUpdateEffect.story.tsx
new file mode 100644
index 0000000000..28650a59bb
--- /dev/null
+++ b/src/__stories__/useUpdateEffect.story.tsx
@@ -0,0 +1,25 @@
+import {storiesOf} from '@storybook/react';
+import * as React from 'react';
+import {useUpdateEffect} from '..';
+
+const Demo = () => {
+  const [count, setCount] = React.useState(0)
+  const [didUpdate, setDidUpdate] = React.useState(false)
+  
+  useUpdateEffect(() => {
+    setDidUpdate(true)
+  }, [count])
+
+  return (
+    <div>
+      <button onClick={() => setCount(count => count + 1)}>Count: {count}</button>
+      <p>Updated: {didUpdate}</p>
+    </div>
+  );
+};
+
+storiesOf('useUpdateEffect', module)
+  .add('Docs', () => <ShowDocs md={require('../../docs/useUpdateEffect.md')} />)
+  .add('Demo', () =>
+    <Demo/>
+  )