What is the difference between HTML and HTML5

To get started with HTML quickly, you only need to master a few basic tags to build a web skeleton. 1. The page structure is essential, and, which is the root element, contains meta information, and is the content display area. 2. Use the title. The higher the level, the smaller the number. Use tags to segment the text to avoid skipping the level. 3. The link uses tags and matches the href attributes, and the image uses tags and contains src and alt attributes. 4. The list is divided into unordered lists and ordered lists. Each entry is represented and must be nested in the list. 5. Beginners don’t have to force memorize all tags. It is more efficient to write and check them while you are writing. Master the structure, text, links, pictures and lists to create basic web pages.

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.

Image not displayed is usually caused by a wrong file path, incorrect file name or extension, HTML syntax issues, or browser cache. 1. Make sure that the src path is consistent with the actual location of the file and use the correct relative path; 2. Check whether the file name case and extension match exactly, and verify whether the image can be loaded by directly entering the URL; 3. Check whether the img tag syntax is correct, ensure that there are no redundant characters and the alt attribute value is appropriate; 4. Try to force refresh the page, clear the cache, or use incognito mode to eliminate cache interference. Troubleshooting in this order can solve most HTML image display problems.

The style placement method needs to be selected according to the scene. 1. Inline is suitable for temporary modification of single elements or dynamic JS control, such as the button color changes with operation; 2. Internal CSS is suitable for projects with few pages and simple structure, which is convenient for centralized management of styles, such as basic style settings of login pages; 3. Priority is given to reuse, maintenance and performance, and it is better to split external link CSS files for large projects.

❌Youcannotnesttagsinsideanothertagbecauseit’sinvalidHTML;browsersautomaticallyclosethefirstbeforeopeningthenext,resultinginseparateparagraphs.✅Instead,useinlineelementslike,,orforstylingwithinaparagraph,orblockcontainerslikeortogroupmultipleparagraph

Pre-resolving DNS can speed up page loading speed, and using HTML link tags for DNS pre-resolving is an effective method; DNSPrefetching saves subsequent request time by resolving domain names in advance; applicable scenarios include third-party fonts, advertising statistics scripts, resource hosting and CDN domain names; it is recommended to prioritize the main page dependency resources, reasonably control the number between 3 and 5, and use it with preconnect to better effect.

Thenameattributeinaninputtagisusedtoidentifytheinputwhentheformissubmitted;itservesasthekeyinthekey-valuepairsenttotheserver,wheretheuser'sinputisthevalue.1.Whenaformissubmitted,thenameattributebecomesthekeyandtheinputvaluebecomesthevalueinthedatasen

Declare the document as HTML5 to avoid the browser from entering weird mode; 2. Define the root element and specify the language to improve accessibility and SEO; 3. It includes ensuring correct character encoding, implementing responsive design, and setting page title; 4. Place all visible content, optionally add CSS, favicon and JavaScript links; this template is complete and compatible with modern browsers, and is suitable for any new HTML file.