Web APIs

Provides the ability to read and write to the system clipboard asynchronously, replacing the older synchronous `execCommand("copy")` approach.

Cookies are small pieces of data stored on the client and sent to the server with every HTTP request. Primarily used for session management, personalization, and tracking.

Provides a way to asynchronously observe changes in the intersection of a target element with an ancestor element or the top-level document's viewport.

Allows you to observe the size of an element's content rect. Useful for building components that adapt to their container size rather than the whole viewport.

The Canvas API provides a means for drawing graphics via JavaScript and the HTML `<canvas>` element. Used for graphs, games, photo manipulation, and real-time video processing.

Allows the user to provide their location to web applications. Provides the device's latitude and longitude through GPS, Wi-Fi, or cellular towers.

Allows web applications to display system-level notifications to the user, even when the browser is in the background.

Allows web apps to trigger a physical vibration on the user's device, primarily used for haptic feedback in mobile games or important alerts.

Both store key-value pairs as strings. `localStorage` persists even after the browser is closed. `sessionStorage` is cleared when the page session ends (e.g., when the tab is closed).

The Broadcast Channel API allows simple communication between different browser contexts (tabs, windows, iframes) on the same origin.

Tells the browser that you wish to perform an animation and requests that the browser calls a specified function to update an animation before the next repaint.

SSE allows servers to push data to web pages over HTTP. Unlike WebSockets, communication is unidirectional (server to client) and lighter-weight.

Web Workers allow you to run script operations in a background thread separate from the main execution thread, preventing the UI from freezing during heavy processing.

WebSockets provide a persistent, full-duplex communication channel between a client and a server, allowing for real-time bidirectional data exchange.

Allows web apps to read, write, and save directly to files and folders on the user's local device, enabling "native-like" IDEs and editors in the browser.

IndexedDB is a low-level API for client-side storage of significant amounts of structured data, including files/blobs. It uses indexes to enable high-performance searches of this data.

Provides the ability to watch for changes being made to the DOM tree (e.g., added children, attribute changes) and react to them.

Enables the scheduling of low-priority work to happen when the browser is idle, preventing foreground tasks (like animations or input) from being interrupted.

The Cache API is a system for storing and retrieving network requests and their corresponding responses. It's often used in combination with Service Workers to support offline experiences.

Browsers limit the amount of storage available to web applications based on disk space and usage. Applications can check current availability using `navigator.storage.estimate()`.

Allows web developers to use a standardized browser-provided interface to handle payment details, reducing friction and increasing conversion rates.

Checklist: feature detect before using, handle permissions/errors gracefully, use workers for non-UI tasks, and always prioritize privacy and security (e.g., use HTTPS).

Event-driven workers registered against an origin and a path. They act as proxy servers between web applications, the browser, and the network, enabling offline usage via caching.

WebGL (Web Graphics Library) is a JavaScript API for rendering high-performance interactive 3D and 2D graphics within any compatible web browser without the use of plug-ins.

Allows web applications and sites to capture and optionally stream audio and/or video media, as well as to exchange arbitrary data between browsers through peer-to-peer (P2P) connections.

A SharedWorker is a type of worker that can be accessed from several different contexts (tabs, iframes) on the same origin, allowing for communal state across tabs.

The MediaRecorder interface provides functionality to easily record media. It's used for capturing audio or video streams from the user's camera/microphone or a `<canvas>` element.

Provides the ability for users to select a screen, window, or tab to capture as a media stream, which can then be recorded or shared over the network.

A powerful and versatile system for controlling audio on the Web, allowing developers to choose audio sources, add effects, and create audio visualizations.

Provides a set of low-level cryptographic primitives (hashing, signature verification, encryption) that are fast and run in the browser's secure environment.