title: React Native: WebView callback on load status
body: <p>Is that possible to get a callback of loading status of a website (eg: 0% to 100%). My purpose is to show a horizontal progress bar whenever a user opens a link.  </p>
  
  <pre><code>import React, { Component } from 'react';
  import { WebView } from 'react-native';
  
  class MyWeb extends Component {
    render() {
      return (
        &lt;WebView
          source={{uri: 'https://github.com/facebook/react-native'}}
          style={{marginTop: 20, width:200, height: 200}}
          newcallback={(percentage)=&gt;{.......}}
        /&gt;
      );
    }
  }
  </code></pre>