miniProgram/@vant/weapp/nav-bar/index.wxml

<wxs src="../wxs/utils.wxs" module="utils" />
<wxs src="./index.wxs" module="computed" />

<view wx:if="{{ fixed && placeholder }}" style="height: {{ height }}px;" />

<view class="{{ utils.bem('nav-bar', { fixed }) }} custom-class {{ border ? 'van-hairline--bottom' : '' }}"
  style="{{ computed.barStyle({ zIndex, statusBarHeight, safeAreaInsetTop }) }}; {{ customStyle }}">
  <view class="van-nav-bar__content">
    <view class="van-nav-bar__left" bind:tap="onClickLeft">
      <block wx:if="{{ leftArrow || leftText }}">
        <van-icon wx:if="{{ leftArrow }}" size="16px" name="arrow-left" custom-class="van-nav-bar__arrow" />
        <view wx:if="{{ leftText }}" class="van-nav-bar__text" hover-class="van-nav-bar__text--hover"
          hover-stay-time="70">{{ leftText }}</view>
      </block>
      <slot wx:else name="left" />
    </view>
    <view class="van-nav-bar__title title-class van-ellipsis">
      <block wx:if="{{ title }}">{{ title }}</block>
      <slot wx:else name="title" />
    </view>
    <view class="van-nav-bar__right" bind:tap="onClickRight">
      <view wx:if="{{ rightText }}" class="van-nav-bar__text" hover-class="van-nav-bar__text--hover"
        hover-stay-time="70">{{ rightText }}</view>
      <slot wx:else name="right" />
    </view>
  </view>
</view>