HTML5, CSS and JavaScript should be efficiently combined with semantic tags, reasonable loading order and decoupling design. 1. Use HTML5 semantic tags, such as improving structural clarity and maintainability, which is conducive to SEO and barrier-free access; 2. CSS should be placed in, use external files and split by module to avoid inline styles and delayed loading problems; 3. JavaScript is recommended to be introduced in front, and use defer or async to load asynchronously to avoid blocking rendering; 4. Reduce strong dependence between the three, drive behavior through data-* attributes and class name control status, and improve collaboration efficiency through unified naming specifications. These methods can effectively optimize page performance and collaborate with teams.

It is a block-level element, suitable for layout; it is an inline element, suitable for wrapping text content. 1. Exclusively occupy a line, width, height and margins can be set, which are often used in structural layout; 2. No line breaks, the size is determined by the content, and is suitable for local text styles or dynamic operations; 3. When choosing, it should be judged based on whether the content needs independent space; 4. It cannot be nested and is not suitable for layout; 5. Priority is given to the use of semantic labels to improve structural clarity and accessibility.

HTML5introducednewinputtypesthatenhanceformfunctionalityanduserexperiencebyimprovingvalidation,UI,andmobilekeyboardlayouts.1.emailvalidatesemailaddressesandsupportsmultipleentries.2.urlchecksforvalidwebaddressesandtriggersURL-optimizedkeyboards.3.num

To get the user's current location, use the HTML5 GeolocationAPI. This API provides information such as latitude and longitude after user authorization. The core method is getCurrentPosition(), which requires successful and error callbacks to be handled; at the same time, pay attention to the HTTPS prerequisite, user authorization mechanism and error code processing. ① Call getCurrentPosition to get the position once, and an error callback will be triggered if it fails; ② The user must authorize it, otherwise it cannot be obtained and may no longer be prompted; ③ Error processing should distinguish between rejection, timeout, location unavailable, etc.; ④ Enable high-precision, set timeout time, etc., and can be configured through the third parameter; ⑤ The online environment must use HTTPS, otherwise it may be restricted by the browser.

The difference between async and defer is the execution timing of the script. async allows scripts to be downloaded in parallel and executed immediately after downloading, without guaranteeing the execution order; defer executes scripts in order after HTML parsing is completed. Both avoid blocking HTML parsing. Using async is suitable for standalone scripts such as analyzing code; defer is suitable for scenarios where you need to access the DOM or rely on other scripts.

The key to using radio buttons in HTML5 is to understand how they work and correctly organize the code structure. 1. The name attribute of each radio button must be the same to achieve mutually exclusive selection; 2. Use label tags to improve accessibility and click experience; 3. It is recommended to wrap each option in a div or label to enhance structural clarity and style control; 4. Set default selections through the checked attribute; 5. The value value should be concise and meaningful, which is convenient for form submission processing; 6. The style can be customized through CSS, but the function needs to be ensured to be normal. Mastering these key points can effectively avoid common problems and improve the effectiveness of use.

The core difference between localStorage and sessionStorage lies in data persistence and scope. 1. Data life cycle: localStorage data is stored for a long time unless manually cleared, and sessionStorage data is cleared after closing the tab; 2. Scope difference: localStorage is shared among all tabs on the same website, and sessionStorage is stored independently; 3. Usage scenario: localStorage is suitable for saving long-term data such as user preferences and login status, sessionStorage is suitable for temporary form data or single session process; 4. API consistency: two operation methods

Yes, it is part of HTML5, but its use has gradually decreased and is controversial. Used to combine the main title with the subtitle so that only the highest level of titles are identified in the document outline; for example, the main title and subtitle can be wrapped in to indicate that they are only auxiliary titles rather than independent chapter titles; however, reasons why they are no longer widely used include: 1. The browser and screen readers are inconsistent support for them, 2. There are simpler alternatives such as using CSS to control styles, 3. The HTML document outline algorithm is not widely supported; despite this, it can still be considered in websites or documents with high semantic requirements; while in most cases, developers tend to use a single, manage styles through CSS and maintain clear title levels.