微信小程序navigationBarTitleText不居中

如果你在微信小程序中使用navigationBarTitleText设置导航栏标题，但是标题不居中，可以尝试以下方法：

1. 设置页面的样式为"navigationStyle":"custom"，这样可以自定义导航栏样式。

2. 在导航栏中添加一个view，并设置该view的flex布局，使标题居中显示。

示例代码如下：

{
  "navigationBarTitleText": "标题",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationStyle": "custom",
  "usingComponents": {},
  "backgroundTextStyle": "dark",
  "backgroundColor": "#f8f8f8",
  "enablePullDownRefresh": false,
  "onReachBottomDistance": 50,
  "navigationBarBackgroundColor": "#fff",
  "navigationBarTextStyle": "black",
  "navigationBarTitleText": "标题",
  "backgroundTextStyle": "dark"
}

在页面的wxml文件中添加以下代码：

<view class="nav-title">{{navigationBarTitleText}}</view>

在页面的wxss文件中添加以下代码：

.nav-title {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
  font-size: 16px;
  font-weight: bold;
}

通过以上方法，可以让标题居中显示。