title: How to bind to textfields without state in react/redux
body: <p>I am a bit new to react/redux</p>
  
  <p>From what I understand state is to be immutable in redux, but when searching for component binding examples I keep seeing things such as</p>
  
  <pre><code>&lt;TextField
    id="usernameId"
    value={this.state.username}    
    onChange={this.handleUsernameChange}
  /&gt;
  
  public handleUsernameChange = (event: any) =&gt; {
          this.setState({
              username: event.target.value
          });
  }
  </code></pre>
  
  <p>To my understanding this is mutating State. When I change the binding to use a global instead. In the callbacks the values are being changed and updated, however the UI is not observing these variables.</p>
  
  <p>I guess this question is just a sanity check.
  Is this acceptable in redux?</p>
  
  <p>Please note I am not using other libraries at the moment</p>
  
  <p>Code I've tried without using state</p>
  
  <pre><code>   let loginInfomation: ILoginInformation = new LoginInformation;
  ...
     &lt;TextField
        id="usernameId"
        value={this.loginInformation.username}    
        onChange={this.handleUsernameChange}
      /&gt;
  
      public handleUsernameChange = (event: any) =&gt; {
            this.loginInfomation.username = event.target.value
         });
      }
  </code></pre>