小编ulm*_*mas的帖子

当我尝试注销时出现此错误。

`core.js:6014 ERROR TypeError: Cannot read property 'length' of undefined
    at http.js:165
    at Array.forEach (<anonymous>)
    at HttpHeaders.lazyInit (http.js:153)
    at HttpHeaders.init (http.js:274)
    at HttpHeaders.forEach (http.js:376)
    at Observable._subscribe (http.js:2342)
    at Observable._trySubscribe (Observable.js:42)
    at Observable.subscribe (Observable.js:28)
    at subscribeTo.js:20
    at subscribeToResult (subscribeToResult.js:7)`

但是当我从邮递员发送 HTTP 请求时，代码就可以工作了。我在使用邮递员时成功退出

我的认证服务

`logout(user){
    let headers = new HttpHeaders({
      'Content-Type': 'application/json',
      'Authorization': this.token }); //this.token is the value of token(eyJhbGciOiJIUzI1NiIsInR5cCI6IkpX...)
  let options = { headers: headers };
    localStorage.clear()
    this.token=null;
    return this.http.post<response>('http://localhost:3000/users/logout',null,options).pipe(map(res=>{
      console.log(res)
       return res
    }))}

` 这是我订阅此 http 请求的代码：

 onLogout(){ …

我正在尝试使用 Visual Studio Code IDE 在我的 PC 中运行下载的离子模板，但当我尝试运行时出现以下错误npm install

> grpc@1.20.0 install C:\Users\Lenovo\Desktop\project\Template-Ionic\ionic-starter-master\node_modules\grpc
> node-pre-gyp install --fallback-to-build --library=static_library

node-pre-gyp WARN Using request for node-pre-gyp https download
node-pre-gyp WARN Tried to download(404): https://node-precompiled-binaries.grpc.io/grpc/v1.20.0/node-v72-win32-x64-unknown.tar.gz
node-pre-gyp WARN Pre-built binaries not found for grpc@1.20.0 and node@12.14.1 (node-v72 ABI, unknown) (falling back to source compile with node-gyp)
gyp ERR! find VS
gyp ERR! find VS msvs_version was set from command line or npm config
gyp ERR! find VS - looking for Visual Studio version …

处理作为错误或通知显示给客户端的消息字符串的最佳实践是什么，以便在打字稿方面和 htlm 中都没有硬代码？

例如，它发生在我身上：在 html 中：

<h1> {{header_message}} </h1>

在打字稿中：

let notificationInfo: string = 'notifications.infoMessage';