RNFS example file operation.js

try {

                            // get a list of files and directories in the main bundle
                            RNFS.readDir(NativeModules.RNFetchBlob.DownloadDir) // On Android, use "RNFS.DocumentDirectoryPath" (MainBundlePath is not defined)
                                .then((result) => {
                                    console.log('GOT RESULT', result);

                                    var promises = []
                                    result.forEach(async (path) => {
                                        console.log("path", path)
                                        promises.push(RNFS.copyFile(path.path, RNFS.DocumentDirectoryPath + "/" + path.name))
                                    })

                                    return promises
                                    // stat the first file
                                    // return Promise.all([
                                    //     RNFS.stat(result[0].path),
                                    //     result[0].path]);
                                })
                                .then((statResult) => {
                                    console.log("=== statResult", statResult)
                                    if (statResult[0].isFile()) {
                                        // if we have a file, read it
                                        return RNFS.readFile(statResult[1], 'base64');
                                    }
                                    console.log("--- no file")
                                    return 'no file';
                                })
                                .then((contents) => {
                                    // log the file contents
                                    //console.log('logging contents', contents);
                                })
                                .catch((err) => {
                                    console.log('error', err.message, err.code);
                                });


                        } catch (err) {
                            console.log("--------err ", err)
                            if (DocumentPicker.isCancel(err)) {
                                // User cancelled the picker, exit any dialogs or menus and move on
                            } else {
                                throw err;
                            }
                        }