chore: rename composables folder

src/composables/use-visibility-change.ts

@@ -0,0 +1,38 @@
+import { inBrowser } from '../utils';
+import { Ref, onDeactivated, onBeforeUnmount } from 'vue';
+import { onMountedOrActivated } from '@vant/use';
+
+// @Experimental
+export function useVisibilityChange(
+  target: Ref<Element | undefined>,
+  onChange: (visible: boolean) => void
+) {
+  // compatibility: https://caniuse.com/#feat=intersectionobserver
+  if (!inBrowser || !window.IntersectionObserver) {
+    return;
+  }
+
+  const observer = new IntersectionObserver(
+    (entries) => {
+      // visibility changed
+      onChange(entries[0].intersectionRatio > 0);
+    },
+    { root: document.body }
+  );
+
+  const observe = () => {
+    if (target.value) {
+      observer.observe(target.value);
+    }
+  };
+
+  const unobserve = () => {
+    if (target.value) {
+      observer.unobserve(target.value);
+    }
+  };
+
+  onDeactivated(unobserve);
+  onBeforeUnmount(unobserve);
+  onMountedOrActivated(observe);
+}