index.js

var React = require('react');
var {Component} = React;
var ReactNative = require('react-native');
var {
    requireNativeComponent,
    NativeModules,
    StyleSheet,
    TouchableWithoutFeedback,
    } = ReactNative;

const blue = '#0084ff';

class FBMessengerButton extends Component {

    render() {
        return (
            <TouchableWithoutFeedback style={[styles.sendToMessengerWrapper, this.props.style]} onPress={this.props.onPress.bind(this)}>
                <RCTFBMessengerButton style={[styles.sendToMessengerWrapper, this.props.style]}/>
            </TouchableWithoutFeedback>
        );
    }
}

FBMessengerButton.propTypes = {
    /**
     * When this property is set to `true` and a valid camera is associated
     * with the map, the camera’s pitch angle is used to tilt the plane
     * of the map. When this property is set to `false`, the camera’s pitch
     * angle is ignored and the map is always displayed as if the user
     * is looking straight down onto it.
     */
    //pitchEnabled: React.PropTypes.bool,
};

var styles = StyleSheet.create({
    sendToMessengerWrapper: {
        width: 300,
        height: 50,
        backgroundColor: blue,
        flex: 1,
        alignSelf: 'center',
    }
});

var RCTFBMessengerButton = requireNativeComponent('RCTFBMessengerButton', FBMessengerButton);

const ShareType = {
    image: 'image',
    gif: 'gif',
    video: 'video',
    audio: 'audio',
};

function send(type, filePath, metadata){
    if(type in ShareType) {
        if(typeof metadata !== 'string'){
            metadata = JSON.stringify(metadata);
        }
        NativeModules.RNFBMessenger.send(type, filePath, metadata);
    } else {
        throw new Error(`
        "${type}" is not a valid type for this method.
            Valid values are: ShareType.image, ShareType.gif, ShareType.video, ShareType.audio`);
    }
}

module.exports = {
    Button: FBMessengerButton,
    backToMessenger: NativeModules.RNFBMessenger.backToMessenger,
    send: send,
    ShareType: ShareType,
};