What are the differences between import and link

The difference between import and link: 1. Purpose and semantics; 2. Loading method; 3. Compatibility; 4. Linking multiple style sheets; 5. Media type; 6. Dynamics; 7. Error handling; 8. Nesting; 9. Default style; 10. Compatibility considerations; 11. Performance considerations; 12. Usage scenarios. Detailed introduction: 1. Purpose and semantics. Link is an HTML tag, used to link to external CSS files or style sheets. It is usually located in the head part of the HTML document, import is part of CSS, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

In HTML and CSS, import and link are both keywords used to introduce external resources, but there are some important differences between them.

1. Purpose and semantics: link is an HTML tag used to link to external CSS files or style sheets. It is usually located in the head section of the HTML document. Import is a part of CSS used to introduce another CSS file into one CSS file. This allows you to split complex styles into smaller, more manageable files.

2. Loading method: When using link to introduce CSS, the browser will load the CSS in order when parsing the HTML document. When importing CSS is used, the browser loads the external stylesheet asynchronously, which means it does not block the parsing of the HTML document.

3. Compatibility: link is part of the HTML standard, so it is supported in all modern browsers. In contrast, import is part of CSS and therefore may not be supported in some older browsers or in certain situations.

4. Link multiple style sheets: Use link to link multiple CSS style sheets. Each style sheet will be loaded and applied in the order in which they appear in the HTML document. It is also possible to link multiple style sheets using import, but they are applied sequentially and later style sheets overwrite previous ones.

5. Media type: link allows specifying different media types (such as screen, print, etc.) to target different output devices and apply different styles. Import does not support media types.

6. Dynamics: Using link, you can dynamically add, delete and change style sheets, while using import, once the CSS file is included, it cannot be easily changed or deleted.

7. Error handling: When using link to introduce an external style sheet, if an error occurs (for example, the URL is incorrect), the browser will ignore the style sheet without interrupting the rendering of the page. However, when using import to introduce an external style sheet, if an error occurs, it will cause the entire style sheet to fail, which means that the page may not render correctly.

8. Nesting: You can use link to nest other HTML elements or style sheets, but you cannot nest style sheets using import. This means that you can use properties from other elements or styles in CSS, but you cannot import one CSS file into another CSS file and use its properties.

9. Default styles: In some cases, style sheets introduced using link will inherit some default styles, while style sheets introduced using import will not inherit these default styles.

10. Compatibility considerations: Since some old browsers may not support the import statement, when compatibility with these browsers is required, link should be used first to introduce external style sheets.

11. Performance considerations: Since using import will block the browser's rendering process, it may not be as good as using link in terms of performance. Especially in large projects, using a large number of import statements may cause the page to load slowly.

12. Usage scenarios: Usually when developing large projects, in order to better organize and manage the code, multiple CSS files are used. In this case, using the import statement can combine these files into a single file, thereby reducing the number of HTTP requests and improving page loading speed. However, for small projects or single pages, it may be simpler and more convenient to use a separate CSS file.

In general, although both import and link can be used to introduce external resources, they have some important differences in terms of usage, semantics, loading methods, compatibility, dynamics, error handling, etc. When choosing which keyword to use, you need to consider factors such as the needs of your project, browser compatibility and performance.

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