[new feature] NavBar: add border prop (#960)

packages/nav-bar/README.md

@@ -56,6 +56,7 @@ export default {
 | right-text | 右侧文案 | `String` | `''` |
 | left-arrow | 是否显示左侧箭头 | `Boolean` | `false` |
 | fixed | 是否固定在顶部 | `Boolean` | `false` |
+| border | 是否显示下边框 | `Boolean` | `true` |
 | z-index | 元素 z-index | `Number` | `1` |
 
 ### Slot

packages/nav-bar/index.ts

@@ -5,10 +5,14 @@ VantComponent({
 
   props: {
     title: String,
+    fixed: Boolean,
     leftText: String,
     rightText: String,
     leftArrow: Boolean,
-    fixed: Boolean,
+    border: {
+      type: Boolean,
+      value: true
+    },
     zIndex: {
       type: Number,
       value: 1

packages/nav-bar/index.wxml

@@ -1,5 +1,5 @@
 <view
-  class="custom-class van-nav-bar van-hairline--bottom {{ fixed ? 'van-nav-bar--fixed' : '' }}"
+  class="custom-class van-nav-bar {{ border ? 'van-hairline--bottom' : '' }} {{ fixed ? 'van-nav-bar--fixed' : '' }}"
   style="z-index: {{ zIndex }}"
 >
   <view class="van-nav-bar__left" bind:tap="onClickLeft">