Basic concepts and usage of IndexedDB

IndexedDB is a browser-side database provided by HTML5, suitable for storing large amounts of structured data. It is based on key-value storage, supports transaction processing, and can work offline. Core concepts include databases, object stores, indexes, and transactions. Databases use a version control mechanism and are opened via the `indexedDB.open` method. Object stores are the basic units for data storage and require a primary key to be specified during creation. Data operations such as addition, deletion, modification, and query must be performed within transactions, which are automatically committed—attention must be paid to their lifecycle. Cursors are used to traverse large datasets. Performance optimizations include batch operations and the rational use of indexes. Error handling must be properly managed. It is suitable for scenarios like offline web applications and client-side caching. Modern browsers generally support it, but compatibility issues should be noted. Developer tools provide debugging support.

Web Storage ('localStorage' and 'sessionStorage')

Web Storage is a client-side storage mechanism introduced in HTML5, which includes two objects: localStorage and sessionStorage. localStorage provides persistent storage, where data remains until manually cleared, with a typical capacity of around 5MB, adhering to the same-origin policy. Its API includes setItem, getItem, removeItem, and clear. sessionStorage shares the same API as localStorage, but the data lifecycle is limited to the current session—data is automatically cleared when the tab is closed. Both can only store strings; objects need to be serialized. Advanced usage includes storage event listeners and performance optimizations like batch operations and data compression. Common issues include insufficient storage space and behavior in private mode. Browser compatibility is excellent, with support across modern browsers. Alternatives include IndexedDB and WebSQL. Security best practices recommend avoiding sensitive information storage and considering data encryption.

The combination of CSS3 animations with HTML5

The combination of CSS3 animations and HTML5 brings rich dynamic effects and interactive experiences to modern web pages. CSS3, through features like transitions, transforms, and animations, along with HTML5's semantic tags and multimedia support, enables the creation of visually appealing and highly functional web applications. The article details the fundamentals of CSS3 animations, including the use of keyframes rules and animation properties, demonstrates the combined effects of transforms and transitions, and explores complex animations integrated with HTML5 video and SVG elements. It also covers responsive animation design and the application of 3D transformations in HTML5 games. Additionally, it emphasizes performance optimization, accessibility considerations, and future trends such as the close integration of CSS Houdini and Web Components with CSS3 animations. Together, these technologies drive the advancement of dynamic web effects.

Introduction to WebGL and Basic Concepts

WebGL is a JavaScript API based on OpenGL ES that enables the rendering of interactive 3D and 2D graphics in browsers. It leverages GPU acceleration directly, requiring no plugins to achieve high-performance graphics processing, and is widely used in fields such as gaming, data visualization, and engineering modeling. Its core technical principles are based on the OpenGL ES 2.0 specification, providing a drawing context through the HTML5 Canvas element. The essence lies in shader programming, using GLSL to write vertex and fragment shaders. The rendering pipeline includes key stages such as vertex processing, primitive assembly, rasterization, and fragment processing. The basic rendering workflow involves obtaining the Canvas element, creating a shader program, initializing buffers, and setting up a rendering loop. WebGL uses a right-handed coordinate system, requiring model, view, and projection matrices for coordinate transformation. Texture mapping is a critical technique in 3D rendering, involving texture creation, parameter setup, and image loading. Lighting models are typically implemented using the Phong model, which includes ambient, diffuse, and specular reflection components. Performance optimization strategies include instanced rendering, buffer management, and shader optimization. Modern WebGL development tools include debugging tools like WebGL Inspector, advanced frameworks like Three.js, and shader editors like ShaderToy. WebGL 2.0 introduces enhanced texture support, advanced shading features, transform feedback, and other capabilities.

The combination of SVG and HTML5

The combination of SVG and HTML5 provides powerful vector graphics processing capabilities for modern web development. Developers can embed SVG elements directly in HTML documents or reference external files to create high-resolution, interactive graphics while maintaining clean code. SVG supports inline embedding and is fully integrated with the DOM, allowing direct manipulation via CSS and JavaScript. SVG elements can be styled with CSS to achieve complex animations, and modern features like CSS filters and variables are also applicable to SVG. JavaScript can dynamically create, modify SVG elements, and add interactive events. Responsive design requires proper use of the `viewBox` attribute and CSS media queries. SVG supports multiple animation techniques, including CSS animations, SMIL, and JavaScript libraries. Filter functions enable various visual effects without relying on external images. Compared to Canvas, SVG is better suited for interactive graphics. SVG sprite technology optimizes multiple icons, and web components can encapsulate SVG as reusable custom elements.

Canvas animation implementation (frame animation, game development, etc.)

Canvas animation is widely used in modern web development, capable of efficiently implementing everything from simple frame animations to complex game scenes. Its core lies in dynamically drawing graphics with JavaScript and leveraging browser rendering mechanisms to achieve smooth visual effects. The basics of frame animation include preparing frame sequences, defining switching intervals, and using requestAnimationFrame. Game development requires optimization techniques such as double buffering to reduce flickering and object pooling to minimize GC pressure. Physics-based animations enable parabolic motion and collision detection to enhance realism. Advanced techniques include particle systems for creating explosion effects and tweening animations for smooth transitions. Performance monitoring ensures smooth operation. Combining WebGL with Canvas 2D allows handling 3D scenes and 2D interface overlays. Together, these technologies build rich web animation experiences.

Canvas image processing (pixel manipulation, filters, etc.)

HTML5 Canvas provides powerful image processing capabilities. Through the `getImageData` and `putImageData` methods, pixel data can be manipulated, with each pixel containing RGBA four components. Basic operations include grayscale conversion and invert effects. Advanced filters use convolution techniques to achieve blur, sharpen, and edge detection. Color adjustments cover brightness, contrast, and hue-saturation transformations. For performance optimization, it is recommended to use Web Workers for processing large images to avoid blocking the UI thread. These technologies offer rich possibilities for web-based image processing.

Canvas drawing API (paths, rectangles, text, etc.)

HTML5's Canvas is a powerful drawing tool that enables rich graphic rendering through its JavaScript API. It supports path drawing, including lines and Bézier curves, and provides a rectangle drawing API for directly rendering, filling, or stroking rectangles. It also supports text rendering with customizable font styles and alignment. The Canvas offers various color and gradient styles, as well as image operations such as basic drawing, scaling, and slicing. It includes graphic transformations like translation, rotation, and scaling, and enables animation effects through continuous clearing and redrawing. Performance optimization techniques, such as offscreen rendering and layer-based drawing, are recommended. Advanced path operations like clipping and hit detection are also supported. Canvas is widely used in scenarios such as data visualization, game development, and image processing.

Basic usage of the '<canvas>' tag

The HTML5 canvas element enables dynamic graphics rendering and animation effects through JavaScript. Basic usage requires obtaining the canvas element and its drawing context. It supports drawing basic shapes like rectangles, paths, and text. Colors and styles can be set using `fillStyle` and `strokeStyle`. Text rendering is done via `fillText` and `strokeText` methods. Image operations include `drawImage` for rendering and pixel-level manipulation. Coordinate transformations are achieved with `translate`, `rotate`, and `scale`. Smooth animations are implemented using `requestAnimationFrame`. Event interaction involves listening to mouse operations. Performance optimization recommendations include layered rendering and offscreen techniques. Practical applications include chart drawing and simple drawing board implementations. Canvas provides powerful pixel-level drawing capabilities, making it suitable for various scenarios such as games and data visualization.

Streaming media and adaptive bitrate technology

Streaming media is a technology that transmits audio and video content over the internet in real-time, allowing users to start playback before the content is fully downloaded. HTML5 natively supports streaming media playback through the `<video>` and `<audio>` tags. Adaptive Bitrate (ABR) technology is a key innovation in the streaming field, dynamically adjusting video quality based on the user's network conditions. HLS (HTTP Live Streaming), developed by Apple, is an ABR protocol that includes components such as a media file segmenter, manifest file generator, and multi-version encoder. DASH (Dynamic Adaptive Streaming over HTTP) is an internationally standardized ABR protocol that uses MPD (Media Presentation Description) files to describe media content. The core of ABR lies in its switching algorithms, with common strategies including buffer-based, bandwidth-based, and hybrid algorithms. To implement ABR, the original video must be encoded into multiple versions. When developing an ABR client player, factors such as segment preloading, bandwidth estimation, and smooth switching must be considered. Media Source Extensions (MSE) is an HTML5 API that allows JavaScript to dynamically generate media streams, serving as a critical technology for enabling ABR.