[Improvement] Tab: scroll to corrent position when sticky & tab change (#389)

packages/tabs/index.vue

@@ -79,6 +79,11 @@ export default {
     curActive() {
       this.scrollIntoView();
       this.setNavBar();
+
+      // scroll to correct position
+      if (this.position === 'page-top' || this.position === 'content-bottom') {
+        scrollUtils.setScrollTop(this.scrollEl, scrollUtils.getElementTop(this.$el));
+      }
     },
 
     sticky(isSticky) {
@@ -90,9 +95,12 @@ export default {
     this.correctActive(this.active);
     this.setNavBar();
 
-    if (this.sticky) {
-      this.scrollHandler(true);
-    }
+    this.$nextTick(() => {
+      if (this.sticky) {
+        this.scrollHandler(true);
+      }
+      this.scrollIntoView();
+    });
   },
 
   beforeDestroy() {

packages/vant-css/src/tab.css

@@ -73,11 +73,12 @@ $van-tabs-card-height: 28px;
 
     .van-tabs__nav {
       overflow-x: auto;
+      overflow-y: hidden;
       -webkit-overflow-scrolling: touch;
 
       &::-webkit-scrollbar {
         display: none;
-        background-color: transparent;
+        background: transparent;
       }
     }
   }