Mobile performance optimization strategies

The key to mobile rendering performance optimization lies in reducing repaints and reflows. It is recommended to use the transform and opacity properties for animations. Network request optimization should focus on reducing HTTP requests, merging files, using sprites, enabling HTTP/2, and preloading. Memory management requires timely unbinding of event listeners to avoid memory leaks caused by closures. Image optimization can employ responsive images and lazy loading techniques. JavaScript execution optimization suggests breaking down long tasks and using Web Workers for intensive operations. Caching strategies include Service Worker offline caching and IndexedDB storage. Touch event optimization involves eliminating click delays by using the touch-action property. Device adaptation requires detecting network status and memory conditions. Code splitting enables on-demand loading. Critical rendering path optimization involves inlining critical CSS and asynchronously loading non-critical resources. Animation performance optimization uses the will-change property, avoids layout thrashing, and ensures smooth 60fps animations.

The basic concept of PWA (Progressive Web App)

Progressive Web Apps (PWAs) combine the strengths of web and native applications, allowing access via browsers without installation, featuring offline functionality and push notifications. Their core components include installability, offline capabilities, responsive design, and push notifications, implemented through technologies like Service Worker, Web App Manifest, and Cache API. PWAs offer advantages such as cross-platform compatibility, no installation required, offline functionality, and convenient updates, but they also face challenges like browser support limitations, feature constraints, and performance optimization. Real-world examples include Twitter Lite, Starbucks, and Pinterest. Development tools like Lighthouse and Workbox streamline the development process. In the future, PWAs may achieve deeper native integration, more robust offline capabilities, and broader application scenarios.

Mobile adaptation solutions (REM, Flexible, etc.)

Mobile adaptation is key to addressing the fragmentation of device screen sizes. Traditional fixed-pixel layouts cannot accommodate diverse screen dimensions. Viewport configuration serves as the foundation of adaptation solutions, using meta tags to control viewport behavior and ensure the viewport width matches the device width. The REM adaptation scheme achieves proportional scaling by adjusting the root element's font size. Flexible.js is a classic implementation that addresses 1px borders and high-DPI screen adaptation. PostCSS plugins can automatically convert values to REM, improving development efficiency. The 1px border issue is resolved through transform scaling for high-DPI screens. Image adaptation involves loading different resolutions based on the device's DPR. Combining flexible layouts with REM yields better results. Dynamic REM calculations can optimize scaling limits for oversized screens. Responsive layouts paired with REM enable precise control. Practical project configurations demonstrate complete Webpack setups. Common challenges include font size adaptation and third-party component compatibility. Modern CSS solutions like vw/vh units are gaining popularity but require attention to compatibility.

Touch events and gesture recognition

HTML5 touch events provide multi-touch interface support for mobile devices, including basic events such as touch start, move, end, and cancel. Through the TouchEvent object, touch point coordinates and identifiers can be obtained to implement common gesture handling like tapping, long-pressing, swiping, and zooming. The article details gesture recognition algorithms, such as calculating the distance between two points and determining swipe direction, as well as performance optimization techniques like event throttling and passive listeners. It also explores using libraries like Hammer.js to simplify development and address cross-platform compatibility issues, along with implementing complex gesture combinations through state management. Finally, it demonstrates practical application scenarios with examples like an image viewer and a sortable list.

Basics of responsive design (Viewport, media queries, etc.)

Responsive design ensures that web pages display well on different devices, with the core elements being viewport settings and media queries. The viewport is controlled via meta tags to adjust the page's scaling ratio, while media queries apply different styles based on screen characteristics. Breakpoint strategies include common device sizes and content-based breakpoints. Responsive image handling uses the `picture` element and `max-width` properties. Mobile-first design involves designing for small screens first and progressively enhancing the experience for larger screens. Responsive layout techniques include Flexbox and Grid layouts. Navigation menus, tables, and font sizes require special handling to adapt to different screens. Testing tools include browser developer tools and actual devices. Performance optimization involves image loading and rendering improvements. Common issues include click delays and viewport unit problems.

The role and usage scenarios of the '<aside>' tag

The HTML5 `<aside>` tag is used to represent content that is indirectly related to the main content of the page, such as sidebars, advertisements, quotes, or notes. It is typically nested within `<article>` or `<body>` as supplementary content without affecting the integrity of the main content. `<aside>` has clear semantic characteristics, which help improve document structure and accessibility. Common use cases include sidebar content, supplementary explanations within articles, and promotional advertisements. When using it, pay attention to its relevance to the context and avoid placing unrelated content. Styling requires separate CSS settings. Browser compatibility is excellent, with all modern browsers supporting it. It can be used in conjunction with other HTML5 tags like `<main>`, `<article>`, and `<nav>`. In practical scenarios, it is often seen on e-commerce product detail pages. For older versions of IE, JavaScript is needed to create the element to ensure compatibility.

The role and usage scenarios of the '<section>' tag

The HTML5 `<section>` tag is a semantic element used to define independent sections within a document, representing a thematic grouping of content. Unlike `<div>`, `<section>` carries explicit semantic meaning and is suitable for logically distinct content blocks. Typical use cases include article segmentation, webpage functional sections, and tabbed content. `<section>` can be nested and is often used alongside semantic tags like `<article>` and `<aside>`. Each `<section>` should include a heading, as it affects the document outline structure. It has specific applications in styling, browser support, ARIA roles, accessibility, single-page applications, CMS systems, microdata, responsive design, and Shadow DOM. Best practices recommend including a heading for each `<section>`, avoiding its use solely for styling, preventing excessive nesting, and ensuring logical content independence. Modern browsers widely support the `<section>` tag.

The role and usage scenarios of the '<article>' tag

The HTML5 `<article>` tag is a semantic element used to mark up independent, self-contained content. It emphasizes the self-sufficiency of the content and is suitable for scenarios like news articles, blog posts, product cards, etc. Unlike `<div>`, `<article>` carries clear semantic value and can be nested, though nesting should be done reasonably. Typical applications include news article bodies, blog system content, and e-commerce product displays. The key difference between `<article>` and `<section>` is that `<article>` emphasizes independence, while `<section>` is used for logical grouping. In practice, avoid misuse such as treating it as a generic container or omitting headings. It can be combined with microdata and ARIA roles to enhance SEO and accessibility. Modern browsers widely support it, though older versions of IE require special handling. It is widely used in CMS systems and SPAs, and correct usage improves document structure and accessibility.

The role and usage scenarios of the '<main>' tag

The HTML5 `<main>` tag is used to identify the main content area of a webpage, enhancing semantics and accessibility. It should contain content directly related to the core theme of the document. Each page should typically have only one visible `<main>` element, and this tag must not be nested within `<article>`, `<aside>`, `<footer>`, `<header>`, or `<nav>` elements. The `<main>` tag helps screen readers quickly locate the primary content and also benefits SEO. Common use cases include the main content area of single-page applications, blog posts, and e-commerce product pages. When using it, developers should be mindful of browser compatibility issues—older versions of IE require polyfill scripts, while modern browsers already provide robust support. Compared to `<div>`, `<main>` carries clear semantic value and is often used in conjunction with semantic tags like `<article>` and `<section>`. Developers should adhere to the uniqueness principle, avoiding multiple visible `<main>` elements, and ensure proper nesting structure to achieve optimal accessibility and code standardization.

The role and usage scenarios of the '<nav>' tag

The HTML5 `<nav>` tag is a semantic element used to define a section of navigation links on a webpage. It clearly distinguishes navigation content from other content, improving document structure and accessibility. It is primarily used for main navigation menus, footer links, breadcrumb trails, and pagination controls. When using it, ensure the `<nav>` tag is only applied to significant navigation groups and enhance accessibility with ARIA attributes. In practical development, it can be combined with responsive design, SVG icons, and dynamic content generation. Additionally, pay attention to browser compatibility and performance optimization, such as reducing nested levels and lazy-loading non-critical navigation. The `<nav>` tag often works alongside other HTML5 elements like `<header>` and `<aside>` to create a clear page structure.