title: How to pick the TextInput onChange event type
body: <p>The case code as below.</p>
  
  <pre><code>import { TextInput } from 'react-native'
  import { reduxAction } from './reduxActionPath'
  
  interface AppProps {
    reduxAction: typeof reduxAction
  }
  
  class CaseComponent extends React.Component&lt;AppProps&gt; {
    // how to define the event type
    handleChange = (str: string) =&gt; (e: whatTheTypeOfE) =&gt; {
      this.props.reduxAction({ [str]: e.target.value })
    }
  
    render(){
      return(
        &lt;TextInput onChange={this.handleChange('userName')} /&gt;
        &lt;TextInput onChange={this.handleChange('password')} /&gt;
      )
    }
  }
  </code></pre>
  
  <p>It should safely check out the type of e, how to pick of it?</p>
  
  <p>UPDATE:
  Now I use the onChangeText to work around of it, but I really want to know how to enable the type of it?</p>
  
  <pre><code>import { TextInput } from 'react-native'
  import { reduxAction } from './reduxActionPath'
  
  interface AppProps {
    reduxAction: typeof reduxAction
  }
  interface AppState {
    userName: string
    userPwd: string
  }
  
  class CaseComponent extends React.Component&lt;AppProps, AppState&gt; {
    render(){
      return(
        &lt;TextInput onChangeText={(userName) =&gt; this.setState({ userName })} /&gt;
        &lt;TextInput onChangeText={(userPwd) =&gt; this.setState({ userPwd })} /&gt;
      )
    }
  }
  </code></pre>