[new feature]: Tab 新增 z-index 属性 (#695)

packages/tab/README.md

@@ -117,6 +117,7 @@ Page({
 |-----------|-----------|-----------|-------------|
 | active | 当前激活标签的索引 | `Number` | `0` |
 | color | 标签颜色 | `String` | `#f44` |
+| z-index | z-index 层级 | `Number` | 99 |
 | type | 样式风格，可选值为`card` | `String` | `line` |
 | border | 是否展示外边框，仅在`line`风格下生效 | `Boolean` | `true` |
 | duration | 动画时间 (单位秒)  | `Number` | `0.2` |

packages/tabs/index.less

@@ -11,7 +11,6 @@
     top: 0;
     left: 0;
     right: 0;
-    z-index: 99;
     position: absolute;
 
     &--page-top {

packages/tabs/index.ts

@@ -45,6 +45,10 @@ VantComponent({
       type: Number,
       value: 0.2
     },
+    zIndex: {
+      type: Number,
+      value: 99
+    },
     swipeThreshold: {
       type: Number,
       value: 4

packages/tabs/index.wxml

@@ -1,5 +1,5 @@
 <view class="custom-class van-tabs van-tabs--{{ type }}">
-  <view class="van-tabs__wrap {{ scrollable ? 'van-tabs__wrap--scrollable' : '' }} {{ type === 'line' && border ? 'van-hairline--top-bottom' : '' }}">
+  <view style="z-index: {{ zIndex }}" class="van-tabs__wrap {{ scrollable ? 'van-tabs__wrap--scrollable' : '' }} {{ type === 'line' && border ? 'van-hairline--top-bottom' : '' }}">
     <scroll-view
       scroll-x="{{ scrollable }}"
       scroll-with-animation