Pros and Cons of Single Page Applications
A Single Page Web Application is a special type of Web application where all activities are confined to a single Web page. Only the respective HTML, JavaScript, and CSS files are loaded during the initialization of the Web page. Once the page is loaded, the SPA doesn't reload or redirect the page. Instead, it dynamically transforms the HTML using JavaScript. By default, the Hash mode uses anchor points to implement routing and to show or hide element components for interaction. Simply put, a SPA application only has one page. In contrast, multi-page applications involve constant navigation between multiple pages, while a single-page application always remains within a single page. In the default Hash mode, routing is achieved using anchor points and controlling the display and hiding of components to simulate page navigation.
Advantages
- Enhanced user interaction: After the initial page load, content changes do not require the entire page to be reloaded, resulting in faster response times. It provides the immediacy of desktop applications, portability, and accessibility akin to websites.
- Decoupling of frontend and backend work: Single-page applications can be used in conjunction with RESTful architecture, using REST API to provide interface data, which helps separate client and server-side work and standardize the use of API.
- Reduced server load: The server does not need to handle page template logic and concatenation. It only needs to provide data after the initial page load, while most calculations are moved to the client side. Single-page applications can increase the server load efficiency.
- High maintainability: It typically involves component-based and modular development, with a high degree of code reusability and relative ease of maintenance.
Disadvantages
- Poor for SEO: Due to frontend rendering, search engines do not parse JavaScript, thus only fetching the unrendered template of the homepage. To improve SEO for single-page applications, SSR (server-side rendering) is typically required. Search engine crawlers can directly view fully rendered pages, but server-side rendering can put strain on the server. SSR server-side rendering is CPU-intensive. However, if only a few pages need SEO, pre-rendering can be used.
- Slow initial load speed: SPA single-page applications usually load all respective HTML, JavaScript, and CSS files on the first page load. This can be optimized using caching measures and lazy loading, where components are loaded on demand.