feat: improve scroll-to-top behavior (#1453)

Co-authored-by: Daniel Roe <daniel@roe.dev>

Author: RYGRIT

app/components/ScrollToTop.client.vue

@@ -3,42 +3,32 @@ const route = useRoute()
 
 // Pages where scroll-to-top should NOT be shown
 const excludedRoutes = new Set(['index', 'code'])
+const isPackagePage = computed(() => route.name === 'package' || route.name === 'package-version')
 
-const isActive = computed(() => !excludedRoutes.has(route.name as string))
+const isActive = computed(() => !excludedRoutes.has(route.name as string) && !isPackagePage.value)
 
 const isMounted = useMounted()
-const isVisible = shallowRef(false)
-const scrollThreshold = 300
+const { scrollToTop, isTouchDeviceClient } = useScrollToTop()
+
+const { y: scrollTop } = useScroll(window)
+const isVisible = computed(() => {
+  if (supportsScrollStateQueries.value) return false
+  return scrollTop.value > SCROLL_TO_TOP_THRESHOLD
+})
 const { isSupported: supportsScrollStateQueries } = useCssSupports(
   'container-type',
   'scroll-state',
   { ssrValue: false },
 )
-
-function onScroll() {
-  if (!supportsScrollStateQueries.value) {
-    return
-  }
-  isVisible.value = window.scrollY > scrollThreshold
-}
-
-function scrollToTop() {
-  window.scrollTo({ top: 0, behavior: 'smooth' })
-}
-
-useEventListener('scroll', onScroll, { passive: true })
-
-onMounted(() => {
-  onScroll()
-})
+const shouldShowButton = computed(() => isActive.value && isTouchDeviceClient.value)
 </script>
 
 <template>
   <!-- When CSS scroll-state is supported, use CSS-only visibility -->
   <button
-    v-if="isActive && supportsScrollStateQueries"
+    v-if="shouldShowButton && supportsScrollStateQueries"
     type="button"
-    class="scroll-to-top-css fixed bottom-4 inset-ie-4 z-50 w-12 h-12 bg-bg-elevated border border-border rounded-full shadow-lg md:hidden flex items-center justify-center text-fg-muted hover:text-fg transition-colors active:scale-95"
+    class="scroll-to-top-css fixed bottom-4 inset-ie-4 z-50 w-12 h-12 bg-bg-elevated border border-border rounded-full shadow-lg flex items-center justify-center text-fg-muted hover:text-fg transition-colors active:scale-95"
     :aria-label="$t('common.scroll_to_top')"
     @click="scrollToTop"
   >
@@ -56,11 +46,11 @@ onMounted(() => {
     leave-to-class="opacity-0 translate-y-2"
   >
     <button
-      v-if="isActive && isMounted && isVisible"
+      v-if="shouldShowButton && isMounted && isVisible"
       type="button"
-      class="fixed bottom-4 inset-ie-4 z-50 w-12 h-12 bg-bg-elevated border border-border rounded-full shadow-lg md:hidden flex items-center justify-center text-fg-muted hover:text-fg transition-colors active:scale-95"
+      class="fixed bottom-4 inset-ie-4 z-50 w-12 h-12 bg-bg-elevated border border-border rounded-full shadow-lg flex items-center justify-center text-fg-muted hover:text-fg transition-colors active:scale-95"
       :aria-label="$t('common.scroll_to_top')"
-      @click="scrollToTop"
+      @click="() => scrollToTop()"
     >
       <span class="i-lucide:arrow-up w-5 h-5" aria-hidden="true" />
     </button>

app/composables/useScrollToTop.ts

@@ -0,0 +1,93 @@
+// Easing function for the scroll animation
+const easeOutQuad = (t: number) => t * (2 - t)
+
+export const SCROLL_TO_TOP_THRESHOLD = 300
+const SCROLL_TO_TOP_DURATION = 500
+
+/**
+ * Scroll to the top of the page with a smooth animation.
+ * @param options - Configuration options for the scroll animation.
+ * @returns An object containing the scrollToTop function and a cancel function.
+ */
+export const useScrollToTop = createSharedComposable(function useScrollToTop() {
+  // Check if prefers-reduced-motion is enabled
+  const preferReducedMotion = useMediaQuery('(prefers-reduced-motion: reduce)')
+
+  /**
+   * Active requestAnimationFrame id for the current auto-scroll animation
+   */
+  let rafId: number | null = null
+  const isScrolling = ref(false)
+
+  /**
+   * Stop any in-flight auto-scroll before starting a new one.
+   */
+  function cancel() {
+    if (rafId !== null) {
+      cancelAnimationFrame(rafId)
+      rafId = null
+    }
+    isScrolling.value = false
+  }
+
+  // Cancel scroll on user interaction
+  const onInteraction = () => {
+    if (isScrolling.value) {
+      cancel()
+    }
+  }
+
+  if (import.meta.client) {
+    const listenerOptions = { passive: true }
+    useEventListener(window, 'wheel', onInteraction, listenerOptions)
+    useEventListener(window, 'touchstart', onInteraction, listenerOptions)
+    useEventListener(window, 'mousedown', onInteraction, listenerOptions)
+  }
+
+  function scrollToTop() {
+    cancel()
+
+    if (preferReducedMotion.value) {
+      window.scrollTo({ top: 0, behavior: 'instant' })
+      return
+    }
+
+    const start = window.scrollY
+    if (start <= 0) return
+
+    isScrolling.value = true
+
+    const startTime = performance.now()
+    const change = -start
+
+    // Start the frame-by-frame scroll animation.
+    function animate() {
+      const elapsed = performance.now() - startTime
+      const t = Math.min(elapsed / SCROLL_TO_TOP_DURATION, 1)
+      const y = start + change * easeOutQuad(t)
+
+      window.scrollTo({ top: y })
+
+      if (t < 1 && isScrolling.value) {
+        rafId = requestAnimationFrame(animate)
+      } else {
+        cancel()
+      }
+    }
+
+    rafId = requestAnimationFrame(animate)
+  }
+
+  tryOnScopeDispose(cancel)
+
+  const isTouchDeviceClient = shallowRef(false)
+  onMounted(() => {
+    isTouchDeviceClient.value = isTouchDevice()
+  })
+
+  return {
+    scrollToTop,
+    cancel,
+    isTouchDeviceClient,
+  }
+})

app/pages/package/[[org]]/[name].vue

@@ -242,6 +242,13 @@ const { copied: copiedVersion, copy: copyVersion } = useClipboard({
   copiedDuring: 2000,
 })
 
+const { scrollToTop, isTouchDeviceClient } = useScrollToTop()
+
+const { y: scrollY } = useScroll(window)
+const showScrollToTop = computed(
+  () => isTouchDeviceClient.value && scrollY.value > SCROLL_TO_TOP_THRESHOLD,
+)
+
 // Fetch dependency analysis (lazy, client-side)
 // This is the same composable used by PackageVulnerabilityTree and PackageDeprecatedTree
 const { data: vulnTree, status: vulnTreeStatus } = useDependencyAnalysis(
@@ -777,26 +784,37 @@ const showSkeleton = shallowRef(false)
               :to="docsLink"
               aria-keyshortcuts="d"
               classicon="i-lucide:file-text"
+              :title="$t('package.links.docs')"
             >
-              {{ $t('package.links.docs') }}
+              <span class="max-sm:sr-only">{{ $t('package.links.docs') }}</span>
             </LinkBase>
             <LinkBase
               v-if="codeLink"
               variant="button-secondary"
               :to="codeLink"
               aria-keyshortcuts="."
               classicon="i-lucide:code"
+              :title="$t('package.links.code')"
             >
-              {{ $t('package.links.code') }}
+              <span class="max-sm:sr-only">{{ $t('package.links.code') }}</span>
             </LinkBase>
             <LinkBase
               variant="button-secondary"
               :to="{ name: 'compare', query: { packages: pkg.name } }"
               aria-keyshortcuts="c"
               classicon="i-lucide:git-compare"
+              :title="$t('package.links.compare')"
             >
-              {{ $t('package.links.compare') }}
+              <span class="max-sm:sr-only">{{ $t('package.links.compare') }}</span>
             </LinkBase>
+            <ButtonBase
+              v-if="showScrollToTop"
+              variant="secondary"
+              :title="$t('common.scroll_to_top')"
+              :aria-label="$t('common.scroll_to_top')"
+              @click="() => scrollToTop()"
+              classicon="i-lucide:arrow-up"
+            />
           </ButtonGroup>
 
           <!-- Package metrics -->