Angular framework is well known for its strong commitment to backward compatibility and long-term stability. From its early versions, the Angular team has followed a carefully planned versioning and deprecation strategy designed to protect large production applications from sudden breaking changes. This approach makes Angular a reliable choice for enterprise systems that require predictable upgrades and extended maintenance cycles.
When the Angular team decides to deprecate a feature, it is not removed immediately. Instead, the feature is first marked as deprecated and continues to function for several subsequent releases. Typically, Angular allows a deprecation window of at least three major releases before completely removing the feature. This policy provides developers sufficient time to refactor their applications, test changes, and plan upgrades without disrupting existing functionality.
Angular follows a strict release schedule in which a new major version is released approximately every six months. Each major release goes through an active maintenance phase lasting six months, during which the Angular team provides bug fixes, performance improvements, and minor enhancements. After the active maintenance period, the version enters a Long Term Support (LTS) phase that lasts for an additional twelve months.
During the combined eighteen-month lifecycle of a major Angular version, breaking changes are avoided. This means developers can safely apply patch updates and minor releases without worrying about sudden incompatibilities. Security fixes and critical bug patches are also backported during the LTS phase, making Angular suitable for applications with strict compliance and security requirements.
For example, if a particular API or feature is marked as deprecated in Angular version 5, it will generally continue to work in versions 6 and 7. The actual removal would typically occur in version 8 or later. This long deprecation cycle is one of the main reasons Angular is trusted by large organizations maintaining complex applications over many years.
Angular also places significant emphasis on documentation and transparency. Each major version of Angular has its own dedicated documentation portal, ensuring that developers working on older applications can still access accurate and version-specific guidance. For instance, documentation for Angular version 7 is available at https://v7.angular.io, allowing teams to reference APIs and behaviors exactly as they existed at that time.
In addition to static documentation, Angular provides a powerful interactive upgrade assistant through the official website https://update.angular.io. This tool allows developers to select their current Angular version and the target version they wish to upgrade to. Based on these inputs, the tool generates a customized step-by-step upgrade guide, highlighting breaking changes, required code modifications, dependency updates, and recommended best practices.
Updating an Angular application from an older version is typically performed using the Angular CLI. The CLI not only updates core framework packages but also applies automated code migrations wherever possible. These migrations are designed to modify deprecated APIs, update configuration files, and align the project with the latest Angular standards.
To update an Angular application written in a previous version, developers should navigate to the project directory and execute the following command:
ng update @angular/cli@8 @angular/core@8
This command updates both the Angular CLI and the Angular core packages to the specified version. During the update process, the CLI analyzes the project, checks installed dependencies, and applies necessary migrations. Developers are often prompted to resolve compatibility issues manually if third-party libraries have not yet been updated to support the target Angular version.
Before performing a major version upgrade, it is recommended to ensure that the application is free of compilation errors and failing tests. Running unit tests and end-to-end tests before and after the upgrade helps identify issues early and ensures that application behavior remains consistent.
Over the years, Angular has introduced several important changes aimed at improving performance, maintainability, and alignment with modern web standards. Some of these changes involved deprecating older APIs and replacing them with more efficient and flexible alternatives.
Below are some of the most significant changes introduced in recent Angular versions that developers should be aware of.
- Removal of HttpModule − The legacy HttpModule and its associated Http service were removed in favor of the more robust HttpClient service provided by the HttpClientModule. The new HTTP client offers a simplified API, built-in JSON parsing, improved error handling, and better support for interceptors. This change encourages a more consistent and modern approach to server communication.
- Removal of deep selectors − The deprecated component style selectors /deep/, >>>, and :ng-deep were removed as part of Angular’s effort to align with standard CSS encapsulation practices. These selectors violated encapsulation boundaries and created maintenance challenges. Developers are now encouraged to use global styles or shared style libraries where cross-component styling is required.
- TypeScript version alignment − Angular tightly controls the supported TypeScript versions to ensure compatibility and stability. For the referenced release, Angular standardized on TypeScript version 3.4. This alignment allows Angular to leverage new TypeScript features while ensuring predictable behavior across different development environments.
- Node.js version requirements − Angular specifies supported Node.js versions to maintain consistency across build and tooling processes. Support for older Node.js versions is dropped as they reach end-of-life. In this case, Angular requires Node.js version 10 or later, ensuring better performance, security, and access to modern JavaScript features.
- Changes in ViewChild and ContentChild behavior − The behavior of @ViewChild() and @ContentChild() decorators changed from dynamic resolution to static resolution by default. This change improves application startup performance and makes component initialization behavior more predictable. Developers must now explicitly specify the static option based on whether the queried element is available during component initialization.
Another notable change involves Angular’s router module, particularly the way lazy-loaded modules are defined. Earlier versions of Angular supported string- based syntax for lazy loading modules. While functional, this approach limited static analysis and tree shaking capabilities.
To address these limitations, Angular removed the string-based lazy loading syntax and introduced a function-based approach using dynamic imports. This modern syntax enables better build optimization, improved error detection, and enhanced compatibility with modern bundlers.
The deprecated string-based syntax looked like the following:
loadChildren: './lazy/lazy.module#LazyModule'
The recommended function-based syntax uses dynamic imports:
loadChildren: () => import('./lazy/lazy.module').then(m => m.LazyModule)
This approach ensures that lazy-loaded modules are fetched only when required and that unused code is excluded from the main application bundle. As a result, applications load faster and scale more efficiently as features are added.
In summary, Angular’s versioning strategy, deprecation policy, and structured upgrade process demonstrate a strong focus on stability and developer trust. By providing clear documentation, automated migration tools, and long support windows, Angular enables teams to evolve their applications gradually without disrupting production systems. Understanding these upgrade principles is essential for maintaining modern, secure, and performant Angular applications over the long term.