title: clearTimeout is not working in React Native
body: <p>I have four screens A (HomePage), B, C, D</p>
  
  <p>Each of screens have a function that will be triggered when the screen <code>onStart</code> or <code>onResume</code>, I achieve it by react-redux.</p>
  
  <pre><code>countdownToFirstScreen = () =&gt; {
      this.timeOut = setTimeout(()=&gt; {
        clearTimeout(this.timeOut); // clearTimeout before navigate next screen
        this.props.leaveTheScreenTime(); // change for some redux store boolean
        this.props.navigation.navigate('A');
      }, 9000);    
    }
  </code></pre>
  
  <p>If user click <code>&lt;Button /&gt;</code> before countdown finish, I set the clearTimeout too.</p>
  
  <pre><code>&lt;Button 
    onPress={() =&gt; { 
      clearTimeout(this.timeOut);
      this.props.navigation.navigate('nextScreen');
    }
  /&gt;
  </code></pre>
  
  <p>It is working when I just navigate between A and B and C.</p>
  
  <p>My issue happens when I try to navigate from C to D.</p>
  
  <p>C screen function <code>countdownToFirstScreen</code> will be triggered eventhough I click the <code>&lt;Button /&gt;</code> on C screen.</p>
  
  <p>Any one knows what happened with my <code>setTimeout</code> and <code>clearTimeout</code>?</p>