var React = require('react-native'); var {   AppRegistry,   StyleSheet,   Text,   View, } = React; var ProgressBar = require('react-native-progress-bar');  var rnsandbox = React.createClass({    getInitialState() {     return {       progress: 0     };   },    render() {      setTimeout((function() {       this.setState({ progress: this.state.progress + (0.4 * Math.random())});     }).bind(this), 1000);      return (       <View style={styles.container}>         <Text style={styles.welcome}>           Welcome to React Native!         </Text>         <Text style={styles.instructions}>           To get started, edit index.ios.js         </Text>         <Text style={styles.instructions}>           Press Cmd+R to reload,{'\n'}           Cmd+Control+Z for dev menu         </Text>         <ProgressBar           fillStyle={{}}           backgroundStyle={{backgroundColor: '#cccccc', borderRadius: 2}}           style={{marginTop: 10, width: 300}}           progress={this.state.progress}         />       </View>     );   } });  var styles = StyleSheet.create({   container: {     flex: 1,     justifyContent: 'center',     alignItems: 'center',     backgroundColor: '#F5FCFF',   },   welcome: {     fontSize: 20,     textAlign: 'center',     margin: 10,   },   instructions: {     textAlign: 'center',     color: '#333333',     marginBottom: 5,   }, });  AppRegistry.registerComponent('rnsandbox', () => rnsandbox);