title: angular2 Universal for backend get hostname
body: <p>client</p>
  
  <pre><code>this._service.get('/api/user').subscribe(user =&gt; {
  
  })
  </code></pre>
  
  <p>server</p>
  
  <pre><code>app.use('/api/user', function(req){
      console.log(req.hostname)  //always get localhost  
  
  })
  </code></pre>
  
  <p>If my check isBrowser no problem ， can get hostname</p>
  
  <pre><code>if( isBrowser )
  {
      this._service.get('/api/user').subscribe(user =&gt; {
          this.store.dispatch({ type: SETUSER, payload: user })
      })
  }
  </code></pre>
  
  <p>How to render in the backend Get the hostname</p>