[improvement] ActionSheet: add z-index prop (#610)

packages/action-sheet/README.md

@@ -88,6 +88,7 @@ Page({
 |-----------|-----------|-----------|-------------|
 | actions | 菜单选项 | `Array` | `[]` |
 | title | 标题 | `String` | - |
+| z-index | z-index 层级 | `Number` | `100` |
 | cancel-text | 取消按钮文字 | `String` | - |
 | overlay | 是否显示遮罩层 | `Boolean` | - |
 | close-on-click-overlay | 点击遮罩是否关闭菜单 | `Boolean` | - |

packages/action-sheet/index.js

@@ -5,6 +5,10 @@ create({
     show: Boolean,
     title: String,
     cancelText: String,
+    zIndex: {
+      type: Number,
+      value: 100
+    },
     actions: {
       type: Array,
       value: []

packages/action-sheet/index.wxml

@@ -1,6 +1,7 @@
 <van-popup
   show="{{ show }}"
   position="bottom"
+  z-index="{{ zIndex }}"
   overlay="{{ overlay }}"
   custom-class="van-action-sheet"
   close-on-click-overlay="{{ closeOnClickOverlay }}"