feat: pull-to-refresh for PWA without native refresh

components/layout.js

@@ -6,6 +6,7 @@ import Footer from './footer'
 import Seo, { SeoSearch } from './seo'
 import Search from './search'
 import styles from './layout.module.css'
+import PullToRefresh from './pull-to-refresh'
 
 export default function Layout ({
   sub, contain = true, footer = true, footerLinks = true,
@@ -14,16 +15,18 @@ export default function Layout ({
   return (
     <>
       {seo && <Seo sub={sub} item={item} user={user} />}
-      <Navigation sub={sub} />
-      {contain
-        ? (
-          <Container as='main' className={`px-sm-0 ${styles.contain}`}>
-            {children}
-          </Container>
-          )
-        : children}
-      {footer && <Footer links={footerLinks} />}
-      <NavFooter sub={sub} />
+      <PullToRefresh>
+        <Navigation sub={sub} />
+        {contain
+          ? (
+            <Container as='main' className={`px-sm-0 ${styles.contain}`}>
+              {children}
+            </Container>
+            )
+          : children}
+        {footer && <Footer links={footerLinks} />}
+        <NavFooter sub={sub} />
+      </PullToRefresh>
     </>
   )
 }

components/pull-to-refresh.js

@@ -0,0 +1,86 @@
+import { useRouter } from 'next/router'
+import { useState, useRef, useEffect, useCallback } from 'react'
+import styles from './pull-to-refresh.module.css'
+
+export default function PullToRefresh ({ children }) {
+  const router = useRouter()
+  const [isRefreshing, setIsRefreshing] = useState(false)
+  const [pullDistance, setPullDistance] = useState(0)
+  const [isPWA, setIsPWA] = useState(false)
+  const touchStartY = useRef(0)
+  const touchEndY = useRef(0)
+
+  useEffect(() => {
+    const checkPWA = () => {
+      // android/general || ios
+      return window.matchMedia('(display-mode: standalone)').matches || window.navigator.standalone === true
+    }
+    setIsPWA(checkPWA())
+  }, [])
+
+  const handleTouchStart = useCallback((e) => {
+    if (!isPWA || window.scrollY > 0) return // don't handle if the user is not scrolling from the top of the page
+    touchStartY.current = e.touches[0].clientY
+  }, [isPWA])
+
+  const handleTouchMove = useCallback((e) => {
+    if (touchStartY.current === 0) return
+    touchEndY.current = e.touches[0].clientY
+    setPullDistance(touchEndY.current - touchStartY.current)
+  }, [])
+
+  const handleTouchEnd = useCallback(() => {
+    if (touchStartY.current === 0 || touchEndY.current === 0) return
+    if (touchEndY.current - touchStartY.current > 300) { // current threshold is 300, subject to change
+      setIsRefreshing(true)
+      router.push(router.asPath)
+      setTimeout(() => {
+        setIsRefreshing(false)
+      }, 500) // simulate loading time
+    }
+    setPullDistance(0) // using this to reset the message behavior
+    touchStartY.current = 0 // avoid random refreshes by resetting touch
+    touchEndY.current = 0
+  }, [router])
+
+  useEffect(() => {
+    if (!isPWA) return
+    document.addEventListener('touchstart', handleTouchStart)
+    document.addEventListener('touchmove', handleTouchMove)
+    document.addEventListener('touchend', handleTouchEnd)
+    return () => {
+      document.removeEventListener('touchstart', handleTouchStart)
+      document.removeEventListener('touchmove', handleTouchMove)
+      document.removeEventListener('touchend', handleTouchEnd)
+    }
+  }, [isPWA, handleTouchStart, handleTouchMove, handleTouchEnd])
+
+  const getPullMessage = () => {
+    if (isRefreshing) return 'refreshing...'
+    if (pullDistance > 300) return 'release to refresh'
+    if (pullDistance > 0) return 'pull down to refresh'
+    return ''
+  }
+
+  return (
+    <div>
+      <div
+        onTouchStart={handleTouchStart}
+        onTouchMove={handleTouchMove}
+        onTouchEnd={handleTouchEnd}
+      >
+        {pullDistance > 0 || isRefreshing
+          ? (
+            <>
+              <p className={`${styles.pullMessage} ${pullDistance > 50 || isRefreshing ? styles.fadeIn : ''}`}>
+                {getPullMessage()}
+              </p>
+              {isRefreshing && <div className={styles.spacer} />}
+            </>
+            )
+          : null}
+        {children}
+      </div>
+    </div>
+  )
+}

components/pull-to-refresh.module.css

@@ -0,0 +1,21 @@
+.pullMessage {
+    position: fixed;
+    left: 50%;
+    top: -50px;
+    transform: translateX(-50%);
+    font-size: 18px;
+    color: #a5a5a5;
+    opacity: 0;
+    transition: opacity 0.3s ease-in-out;
+    text-align: center;
+}
+
+.fadeIn {
+    opacity: 1;
+    top: 0;
+}
+
+.spacer {
+    position: relative;
+    margin-bottom: 32px;
+}