In the Angular server-side rendering scenario, the HTML source code rendered by the server and the HTML source code rendered by the client may not be completely consistent, which is caused by the following reasons:
Components loaded asynchronously
There may be some asynchronously loaded components in the Angular application. These components may not be loaded when the server is rendered, so the HTML content rendered by the server may not contain the content of these components, and the client-side rendering will be completed after loading. Render these components again.
browser specific code
Some codes can only be executed in the browser environment, such as direct manipulation of DOM, event monitoring, etc. These codes cannot be executed during server-side rendering, so server-side rendered HTML content may not contain these codes, while client-side rendering will re-execute these codes in the browser environment.
User interaction
After the server-side rendering is complete, the user may interact with the application, such as submitting a form, switching routes, etc. These operations may cause the state of the application to change, thereby affecting the rendering result of the application. Therefore, server-rendered HTML content may not exactly match client-rendered HTML content.
In order to ensure the consistency of the two rendering methods as much as possible, some measures can be taken, such as using pre-rendering when loading components asynchronously, avoiding direct manipulation of DOM in components, and so on. In addition, some additional processing can be performed on the server-side rendering result so that the client-side rendering can better match the server-side rendering result.
What is pre-render technology in the field of Angular server-side rendering
The pre-rendering technology in the field of Angular server-side rendering refers to rendering some pages of the application in advance on the server side, saving the rendering results, and then directly returning the pre-rendered HTML content when the client requests these pages , avoiding the need for the client to re-render.
Specifically, pre-rendering techniques are usually done during the application build process. During the construction process, the pre-renderer simulates the browser environment, accesses certain routes of the application, and saves the access results to static files. When the client requests these routes, the server directly returns the pre-rendered static HTML file, thus avoiding the need for the client to re-render, and improving the page loading speed and user experience.
The application scenarios of pre-rendering technology are usually pages with relatively static content, such as blogs and news, because the content of these pages does not change frequently, and pre-rendering can be performed during the construction process. For some pages with relatively dynamic content, such as a search result page that needs to be dynamically generated based on user input, the pre-rendering technology may not be applicable.
It should be noted that the pre-rendering technology cannot completely solve the inconsistency between server-side rendering and client-side rendering, because in the process of pre-rendering, specific information of the client environment cannot be obtained, such as the user's device type, browser Server information, etc., which may cause the pre-rendered HTML content to be inconsistent with the client-rendered result. Therefore, when using pre-rendering technology, it needs to be selected and used according to specific scenarios and needs.