improvement on progress bar - https://github.com/lwansbrough/react-native-progress-bar

progress-bar.js

import React, {
  Component,
} from 'react';

import {
    StyleSheet,
    Text,
    View,
    Animated,
    Easing,
} from 'react-native';

export default class ProgressBar extends Component {
  constructor(props) {
    super(props);

    this.state = {
      progress: new Animated.Value(this.props.initialProgress || 0),
    };

    this.props.style          = styles;
    this.props.easing         = Easing.linear(Easing.ease);
    this.props.easingDuration = 100;
  }

  componentDidUpdate(prevProps, prevState) {
    if (this.props.progress >= 0 && this.props.progress != prevProps.progress) {
      this.update();
    }
  }

  render() {
    let fillWidth = this.state.progress.interpolate({
      inputRange: [0, 1],
      outputRange: [0 * this.props.style.width, 1 * this.props.style.width],
    });

    return (
      <View style={[styles.background, this.props.backgroundStyle, this.props.style]}>
        <Animated.View style={[styles.fill, this.props.fillStyle, { width: fillWidth }]}/>
      </View>
    );
  }

  update() {
    Animated.timing(this.state.progress, {
      easing: this.props.easing,
      duration: this.props.easingDuration,
      toValue: this.props.progress / 100
    }).start();
  }
}

var styles = StyleSheet.create({
  background: {
    backgroundColor: '#bbbbbb',
    height: 4,
    overflow: 'hidden'
  },
  fill: {
    backgroundColor: '#3b5998',
    height: 4
  }
});

It's not working. If I am passing progress value but I can't see it filled.