flat: 性能优化，animation 等\preload等

hook/page-animation.css

@@ -0,0 +1,30 @@
+/* #ifdef H5 */
+uni-page {
+    opacity: 1;
+    will-change: opacity;
+}
+
+/* --- 进场 (Enter) --- */
+uni-page.animation-enter-from {
+    opacity: 0;
+}
+
+uni-page.animation-enter-active {
+    transition: opacity 0.2s ease-out;
+}
+
+/* --- 离场 (Leave) --- */
+uni-page.animation-leave-active {
+    transition: opacity 0.15s ease-in;
+}
+
+uni-page.animation-leave-to {
+    opacity: 0;
+}
+
+/* --- 稳态 --- */
+uni-page.animation-show {
+    opacity: 1;
+}
+
+/* #endif */

hook/usePageAnimation.js

@@ -0,0 +1,66 @@
+import {
+    onLaunch
+} from '@dcloudio/uni-app'
+import {
+    getCurrentInstance
+} from 'vue'
+import './page-animation.css'
+
+const DURATION = 130
+
+export default function usePageAnimation() {
+    // #ifdef H5
+    const show = () => {
+        const page = document.querySelector('uni-page')
+        if (!page) return
+        const cl = page.classList
+
+        cl.add('animation-enter-from')
+        cl.remove('animation-leave-to', 'animation-leave-active')
+
+        requestAnimationFrame(() => {
+            requestAnimationFrame(() => {
+                cl.remove('animation-enter-from')
+                cl.add('animation-enter-active', 'animation-show')
+
+                setTimeout(() => {
+                    cl.remove('animation-enter-active')
+                }, DURATION)
+            })
+        })
+    }
+
+    const hide = (next) => {
+        const page = document.querySelector('uni-page')
+        if (!page) {
+            next()
+            return
+        }
+        const cl = page.classList
+
+        cl.add('animation-leave-active')
+
+        requestAnimationFrame(() => {
+            cl.remove('animation-show')
+            cl.add('animation-leave-to')
+
+            setTimeout(() => {
+                cl.remove('animation-leave-active', 'animation-leave-to')
+                next()
+            }, DURATION - 50)
+        })
+    }
+
+    onLaunch(() => {
+        const instance = getCurrentInstance()
+        const router = instance?.proxy?.$router
+        if (router) {
+            show()
+
+            router.beforeEach((to, from, next) => hide(next))
+
+            router.afterEach(() => show())
+        }
+    })
+    // #endif
+}