Principles and optimization of html page rendering_html/css_WEB-ITnose

The approximate process of loading an html web page

1. The user enters the URL (assuming it is the first visit), the browser sends a request to the server, and the server returns the html file.

2. The browser starts loading the html code and finds that there is a link tag in the head tag that refers to the external css file.

3. The browser sends a request for the css file again, and the server returns the css file.

4. The browser continues to load the code in , and the css code has been obtained, and the interface starts to be rendered.

5. The browser finds an tag in the code that references an image and sends a request to the server. The browser does not wait until the image is downloaded, but continues to render the following code.

6. The server returns the image file. Since the image occupies a certain area and affects the subsequent layout, the browser needs to go back and re-render this part of the code.

7. The browser found a line of <script> code in js code and quickly executed it. </script>

The 8.js script executes this statement, which instructs the browser to hide a certain