Boost your Angular app with server-side rendering
Table of Contents
- Introduction
- What is Server-Side Rendering?
- When Do You Need to Use Server-Side Rendering?
- Server-Side Rendering in Angular vs React
- Pros and Cons of Server-Side Rendering
- How to Implement Server-Side Rendering in Angular
- Installation of Additional Package
- Changes in the Package.json File
- Exploring the Changes in the Source Folder
- Understanding the App Server Module
- Introduction to the Express Server
- Overcoming Challenges with Server-Side Rendering
- Addressing Issues with Local Storage
- Receiving Initial State from the Server
- Reducing State from Server to Client
- Conclusion
📗 Introduction
In this article, we will delve into the concept of server-side rendering (SSR) and its implementation in Angular. We will explore what SSR is, when it is necessary to use it, and the comparison between SSR in Angular and React. Additionally, we will discuss the pros and cons of SSR and guide you through the process of implementing SSR in your Angular application. So, let's get started!
📕 What is Server-Side Rendering?
Server-side rendering (SSR) is the process of rendering a web page or application on the server and sending the fully rendered page to the client. Unlike traditional client-side rendering, where the page is initially empty and then built using JavaScript, SSR ensures that the page is rendered on the backend. This has several advantages, including improved search engine optimization (SEO) as the page can be indexed by search engines, faster time to content for users, and better performance on low-end devices.
📗 When Do You Need to Use Server-Side Rendering?
Server-side rendering is particularly useful when you want your web application to be accessible to search engines for indexing purposes. By rendering the application on the server, search engines can crawl and index the content, making it more discoverable to users. Additionally, SSR can improve the initial loading speed of your application, as the user doesn't have to wait for the JavaScript to be parsed and executed before seeing the content.
📘 Server-Side Rendering in Angular vs React
When comparing server-side rendering in Angular and React, it's important to note that server-side rendering in Angular is less common compared to React. However, Angular's server-side rendering capability is equally robust, allowing you to render your application on the server and provide an enhanced user experience.
📙 Pros and Cons of Server-Side Rendering
Server-side rendering in Angular has both advantages and disadvantages, which we will discuss in this section.
Pros of Server-Side Rendering
- Improved SEO: By rendering the application on the server, search engines can easily crawl and index the content, improving its discoverability.
- Faster time to content: With server-side rendering, users can see the content of the page more quickly, as they don't have to wait for JavaScript to be parsed and executed.
- Better performance on low-end devices: Server-side rendering reduces the amount of processing required on the client-side, leading to better performance on devices with limited resources.
Cons of Server-Side Rendering
- Complexity: Server-side rendering involves additional setup and configuration, making it more complex compared to client-side rendering.
- Increased server load: Rendering the application on the server can increase the load on the server, especially during high traffic periods.
- Limited interactivity: Server-side rendering may limit the interactivity of your application, as some features heavily rely on client-side JavaScript execution.
📗 How to Implement Server-Side Rendering in Angular
To implement server-side rendering in Angular, we will follow a step-by-step process. Let's go through each step in detail:
Step 1: Installation of Additional Package
To enable server-side rendering in your Angular application, you need to install an additional package. Open your terminal and run the following command:
ng add @nguniversal/express-engine
This command will add the necessary package to your package.json and generate the required files for the server-side rendering engine.
Step 2: Changes in the Package.json File
After installation, you will notice several changes in your package.json file. You will see the @nguniversal/express-engine package listed as a dependency, and four new commands - serve, build, prerender, and dev:ssr - will be added under the scripts section.
Step 3: Exploring the Changes in the Source Folder
Inside your source folder, you will find a new file named main.server.ts. This file is similar to the main.ts file, but it is specifically used for server-side rendering. It includes the AppModule from your application and a server module from the angular/platform-server package.
Step 4: Understanding the App Server Module
In addition to the main.server.ts file, you will also find a new file named app.server.module.ts. This module is used on the server-side and imports everything from your regular AppModule. This allows you to reuse the same code and logic on both the server and the client.
Step 5: Introduction to the Express Server
The most important file generated during the server-side rendering setup is the server.ts file. This file contains an Express server that handles the rendering of your Angular application on the backend. It includes various declarations and imports, with the key part being the use of the ngExpressEngine
function.
Step 6: Overcoming Challenges with Server-Side Rendering
During the implementation of server-side rendering, you may encounter challenges such as issues with local storage. Since local storage does not exist on Express or any backend environment, you need to make adjustments to your code accordingly. By injecting the platformId
and using if conditions, you can ensure that certain code only runs on the client-side.
Step 7: Addressing Issues with Local Storage
To address the issue of local storage not being available on the server-side, you can inject the platformId
and check if the rendering is happening on the client-side. By using the isPlatformBrowser
function, you can selectively execute code that relies on local storage only when running on the client-side.
Step 8: Receiving Initial State from the Server
One of the advantages of server-side rendering is the ability to send initial state data from the server to the client. By using the TransferState
service, you can store the initial state on the server and retrieve it on the client-side. This eliminates the need to make redundant API calls when the data is already available during server-side rendering.
Step 9: Reducing State from Server to Client
To reduce the state from the server to the client, you can utilize the TransferState
service. After setting the state on the server-side, you can check if the data already exists on the client-side before making additional API calls. By employing this technique, you can reuse the state received during server-side rendering, resulting in improved performance and reduced data-fetching overhead.
📘 Conclusion
In this article, we explored the concept of server-side rendering (SSR) in Angular and learned how to implement it in our applications. We discussed the importance of SSR for SEO and improved performance, compared SSR in Angular to React, and discussed the pros and cons of server-side rendering. Additionally, we walked through the step-by-step process of setting up server-side rendering in an Angular application. By following the guidelines provided, you can leverage the power of server-side rendering to enhance the user experience of your Angular applications.
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