Server-Side Rendering (SSR) in Angular refers to the process of rendering Angular applications on the server, generating the initial HTML content that's sent to the client's browser. This contrasts with the default client-side rendering approach, where the browser fetches the application code and executes it to render the content.
How SSR Works in Angular:
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Server-Side Rendering Process:
- When a request is made to the server for an Angular application, the server executes the Angular application code.
- Angular Universal, the server-side rendering solution for Angular, pre-renders the application, generating the initial HTML on the server.
- This initial HTML, along with necessary JavaScript bundles, is sent to the client's browser.
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Client-Side Hydration:
- Once the initial HTML is received by the browser, the JavaScript bundles contain the necessary code to bootstrap the Angular application.
- The client-side JavaScript code takes over, rehydrating the pre-rendered content and making the application interactive.
- Angular on the client-side takes control, enabling further interactions and rendering subsequent views as a Single Page Application (SPA).
Benefits of Server-Side Rendering in Angular:
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Improved Performance and SEO:
- SSR provides faster initial page load times by sending pre-rendered content, enhancing perceived performance.
- Search engine crawlers can easily index the pre-rendered content, improving search engine optimization (SEO) for Angular applications.
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Enhanced User Experience:
- Faster initial rendering improves the user experience, especially on slower devices or network connections.
- It enables users to view content even if JavaScript execution is delayed or disabled.
Implementing SSR in Angular:
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Angular Universal:
- Angular Universal is the official solution for server-side rendering in Angular.
- It provides utilities and APIs to perform server-side rendering and handle the complexities of running Angular on the server.
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Setting up Angular Universal:
- To enable SSR, Angular projects need to be configured with Angular Universal. This involves installing the necessary packages and modifying the application to support server-side rendering.
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Usage with Angular CLI:
- Angular CLI has support for Angular Universal, allowing you to create, build, and serve Universal applications using CLI commands.
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Commands like
ng add @nguniversal/express-engine and ng run your-app:serve-ssr
can help set up and serve SSR-enabled Angular applications.
Considerations:
- SSR adds complexity to the application setup and development process.
- Not all Angular features and libraries might work seamlessly with SSR due to the differences between server and client environments.
- Careful handling of browser-specific functionalities and external libraries is required for SSR compatibility.
SSR in Angular offers significant performance and SEO benefits, making it a valuable approach for certain types of applications, especially those requiring enhanced initial load times and better search engine visibility.