Check application version prepare_app_to_start program

prepare_app_to_start.dart

// Path to the web root
const webRoot = '/usr/share/nginx/html';
// Locations of the Web application files we are going to update
const indexHtmlPath = '$webRoot/index.html';
const flutterJsPath = '$webRoot/flutter.js';
const versionJsonPath = '$webRoot/version.json';

// Compose app version by adding build_number
final versionJsonFile = File(versionJsonPath);
final versionJson = jsonDecode(await versionJsonFile.readAsString());
final appVersion = '${versionJson['version']}b${versionJson['build_number']}'.trim();

// Update flutter.js file by specifying app version to the main.dart.js
final flutterJsFile = File(flutterJsPath);
final flutterJsContent = await flutterJsFile.readAsString();
final flutterJsReplaced = flutterJsContent.replaceAll('main.dart.js', 'main.dart.js?$appVersion');
await flutterJsFile.writeAsString(flutterJsReplaced);

// Update index.html file by specifying app version to the flutter.js file
final indexHtmlFile = File(indexHtmlPath);
final indexHtml = await indexHtmlFile.readAsString();
final indexHtmlReplaced = indexHtml.replaceAll('"flutter.js"', '"flutter.js?$appVersion"');
await indexHtmlFile.writeAsString(indexHtmlReplaced);