Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

关于render函数内变量赋值为null #2148

Closed
zhulingchaodean opened this issue Feb 13, 2019 · 3 comments
Closed

关于render函数内变量赋值为null #2148

zhulingchaodean opened this issue Feb 13, 2019 · 3 comments
Labels
question Further information is requested

Comments

@zhulingchaodean
Copy link

zhulingchaodean commented Feb 13, 2019

您好请教一下:

render(){
   let isLoggedIn = true;
    // const isLoggedIn = this.props.isLoggedIn
    // 这里最好初始化声明为 `null`,初始化又不赋值的话
    // 小程序可能会报警为变量为 undefined
    let status = null
    if (isLoggedIn) {
     status = <Text>已登录</Text>
    } else {
     status = <Text>未登录</Text>
    }
   return (
      <View>{status}</View> 
  )
}

这段是在官方文档上复制下来的 当中 条件判断一定要使用 props 传递值吗?
自己定义变量后 渲染在页面上的却是 null

@taro-bot
Copy link

taro-bot bot commented Feb 13, 2019

欢迎提交 Issue~

如果你提交的是 bug 报告,请务必遵循 Issue 模板的规范,尽量用简洁的语言描述你的问题,最好能提供一个稳定简单的复现。🙏🙏🙏

如果你的信息提供过于模糊或不足,或者已经其他 issue 已经存在相关内容,你的 issue 有可能会被关闭。

Good luck and happy coding~

@luckyadam
Copy link
Member

let isLoggedIn = true

isLoggedIn 的值已经确定了,那下面的判断就毫无意义,用作条件判断的东西可以是来自 props 也可以来自 state,或者是定义的变量,但是不能是一个确定的值

@taro-bot
Copy link

taro-bot bot commented Apr 8, 2019

Hello~

您的问题楼上已经有了确切的回答,如果没有更多的问题这个 issue 将在 15 天后被自动关闭。

如果您在这 15 天中更新更多信息自动关闭的流程会自动取消,如有其他问题也可以发起新的 Issue。

Good luck and happy coding~

@taro-bot taro-bot bot removed the to be closed label Apr 12, 2019
@taro-bot taro-bot bot closed this as completed Apr 12, 2019
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Labels
question Further information is requested
Projects
None yet
Development

No branches or pull requests

3 participants