What is the basic syntax of comment tags in HTML

MetatagsareessentialforSEOandshouldbeoptimizedproperly.1.Usetherighttitletagbymakingitconcise,descriptive,andkeyword-rich,ideallyunder60characters.2.Don’tskipthemetadescription;keepitcompelling,relevant,andwithin150–160characterstoimproveclick-throug

ShadowDOM is a technology used in web component technology to create isolated DOM subtrees. 1. It allows the mount of an independent DOM structure on ordinary HTML elements, with its own styles and behaviors, and does not affect the main document; 2. Created through JavaScript, such as using the attachShadow method and setting the mode to open; 3. When used in combination with HTML, it has three major features: clear structure, style isolation and content projection (slot); 4. Notes include complex debugging, style scope control, performance overhead and framework compatibility issues. In short, ShadowDOM provides native encapsulation capabilities for building reusable and non-polluting UI components.

Tags in HTML are the core tools for creating web page hyperlinks, which are used to jump pages, locate content, send emails, etc. 1. Basic usage: specify the target address through the href attribute, and support relative paths and absolute paths; 2. Jump within the page: Use #id to implement anchor positioning to improve user experience; 3. Multi-functional applications: support mailto: sending emails, tel: dialing, downloading files; 4. Opening a new window: Combining target="_blank" and rel="noopener" to ensure security. Mastering these key points allows you to flexibly control web navigation behavior.

When the browser parses the picture elements, matches in the source order, and finds the first supported resource loading, otherwise it falls back to img. Because the browser checks from top to bottom whether each source meets the criteria, it stops once it matches, and neither the subsequent source nor the img will be loaded. The correct order should be to place the loaded format in the front, such as AVIF, WebP, and alternative formats such as JPG, PNG, and img as the final guarantee. Common problems include img without src, source type error or path error, causing fallback to fail. It is recommended to verify the source order, check the img path, and use developer tools to debug resource loading.

The order of source tags in the picture element directly affects the priority of the browser's loading resources. The correct order should be: 1. Put modern formats with high priority (such as AVIF, WebP) in front; 2. Put the formats with good compatibility (such as JPG) in back; 3. The img tag must set the src attribute as the final bottom-up solution. The browser will check the conditions of each source from top to bottom. Once it is met, it will load the corresponding resource and stop judging the subsequent source. Therefore, if the compatible format is written in the front, modern formats may never be loaded. Common errors include reverse order, missing type attributes, or src without img, which will cause optimization failure or even the image cannot be displayed.

The link tag is used in web development to introduce external resources, and its core uses include introducing CSS files, adding website icons, preloading key resources, and referencing RSSFeed. First, use rel="stylesheet" to introduce CSS files to unify page styles; second, add multi-size favicon to improve user experience through rel="icon"; third, use rel="preload" to load key resources such as fonts in advance to improve performance, but use it with caution; finally, declare RSSFeed through rel="alternate" to facilitate content aggregation

Yes, it is correct and recommended to use, but you also need to make sure that the actual encoding of the file is consistent with the server configuration. 1. Place the tag in the HTML document and try to be in front of it to ensure that the browser parses correctly; 2. Make sure that the text editor or IDE saves the file as UTF-8 encoding to avoid character display errors; 3. Check whether the server sends the correct character set through HTTP headers, such as setting charset=utf-8 in Apache, Nginx configuration or back-end code; 4. UTF-8 supports most languages and symbols, and has replaced the old encoding format as a modern web standard.

document.write() is a method used in JavaScript to insert content into HTML pages, but there are great risks. The core problem is that the call will clear the current document after the page is loaded; it affects performance and maintainability; it is not conducive to SEO; it is not suitable for modern development frameworks. Therefore, use in actual projects should be avoided and instead adopt DOM operations or update mechanisms provided by modern frameworks.