In the early days of web development, the use of server-side languages like PHP, Java, Perl, combined with HTML and CSS were the norm, with a sprinkle of JavaScript as an optional ingredient. However, around 2005, the widespread adoption of AJAX (Asynchronous JavaScript and XML) revolutionized web development by allowing data to be updated asynchronously by exchanging data with a web server behind the scenes. This meant that it was possible to update parts of a web page, without reloading the whole page. While AJAX was a big step forward, dealing with different browsers was still a headache for developers.

To address this, jQuery was introduced in 2006/2007, which made it easier to handle DOM manipulations, event handling, and AJAX. However, there was still no concept of modules in the front-end world, making code hard to maintain and organize.

The Rise of Single-Page Applications (SPAs)

During the 2010s, we witnessed the remarkable rise of Single-Page Applications (SPAs) in the realm of web development. SPAs revolutionized the way we interacted with websites by providing a seamless and dynamic user experience. Unlike traditional multi-page websites, SPAs loaded the entire application upfront and dynamically updated the content as users navigated through the site, eliminating the need for page reloads. This approach gained immense popularity due to its ability to create fast, responsive, and interactive web applications.

One of the key advantages of SPAs was their ability to deliver a smoother user experience. With SPAs, users no longer had to wait for the entire page to reload when they clicked on a link or performed an action. The application responded instantaneously, resulting in a highly responsive interface that felt more like a native app than a traditional website. This improved performance was made possible by leveraging advanced JavaScript frameworks such as React and Angular, which enabled efficient rendering of components and managing state changes without refreshing the entire page. SPAs became the preferred choice for many modern web applications, including social media platforms, project management tools, and collaborative editing applications, to name just a few.

Another significant advantage of SPAs was their ability to add structure to the code base and bring order to chaos. With SPAs, developers could organize their code into reusable components, making it easier to maintain and update. The modular nature of SPAs allowed for a more efficient development process, with different teams or developers working on specific components independently. This modular approach also enhanced code reusability, reducing duplication and promoting a more structured and scalable codebase. As a result, SPAs brought a sense of organization and maintainability to web development projects, improving overall development efficiency and long-term code quality.

However, the rise of SPAs also brought about new challenges, particularly concerning performance and SEO.

The Need for Server-Side Rendering (SSR)

Single Page Applications (SPAs) bring about unique challenges when it comes to performance and search engine optimization (SEO). Due to their dynamic nature, SPAs rely heavily on JavaScript to handle client-side rendering and data fetching. This can lead to slower initial page loads and increased time for content to become visible, which negatively impacts user experience. Additionally, some traditional search engine crawlers have difficulty parsing and indexing JavaScript-generated content, resulting in reduced discoverability in search engine rankings.

To address these issues, server-side rendering (SSR) was introduced. SSR involves rendering components on the server and sending the pre-rendered HTML to the client for faster initial page load. While the user interacts with the page, the JavaScript bundles load in the background and take over when they are ready, giving users a chance to view the application UI before it becomes fully interactive.

Angular Universal - The SSR Solution for Angular

Angular Universal is a server-side rendering (SSR) solution provided by the Angular framework. It allows developers to run their Angular applications on the server, generating fully rendered HTML pages that can be delivered to the client. Unlike traditional Angular applications that rely on client-side rendering, Angular Universal pre-renders the initial view on the server, improving performance and enhancing the user experience. By rendering the content on the server, Angular Universal assists search engines in more easily crawling and indexing the application, potentially improving SEO performance. It also provides better support for social media sharing and improves the application’s initial load time.

Before version 16, Angular Universal used destructive hydration for SSR. This means the application would be rendered using SSR on the server and then re-rendered from scratch in the browser, often causing a flickering issue. However, Angular 16 introduced full app non-destructive hydration, also known as Partial DOM Hydration. Although it’s still in developer preview and not production-ready, this feature promises to reuse the initial DOM, sharing server state with the client and thus avoiding duplicate API calls and flickering issues.

Pros and Cons of Angular Universal

Like every technology, Angular Universal has its strengths and weaknesses. Understanding these trade-offs is key to deciding if it’s the right tool for your project.

Pros:

1. Improved Initial Load Time: By pre-rendering the application on the server, Angular Universal can deliver the initial view to users faster, improving the perceived performance.
2. Better SEO: As the pre-rendered pages include all necessary HTML, they are easier for search engine crawlers to parse and index.
3. Faster First Contentful Paint (FCP): The FCP metric measures the time from navigation to the time when the browser renders the first bit of content from the DOM. Server-side rendering can significantly improve this metric.

Cons:

1. Complexity: Implementing SSR with Angular Universal adds an extra layer of complexity to your application. You’ll need to ensure that your application runs correctly in both the browser and server environments.
2. Cost: Server-side rendering is more CPU-intensive than client-side rendering. As a result, it may lead to increased server costs.
3. Limited Browser APIs: When running on the server, there is no document or window object, and use of browser-specific APIs will throw errors. You’ll need to check if these APIs are available before using them or use Angular’s platform-specific APIs instead.

While JavaScript and its ecosystem continue to evolve, Angular Universal offers a powerful solution to the challenges posed by SPAs. By pre-rendering applications on the server, Angular Universal improves performance, enhances SEO, and offers a smoother user experience. Developers, however, must carefully weigh these benefits against the added complexity and server load that comes with SSR.