Jint

Supported features ​

Jint.Browser is intended for script-driven DOM automation and extraction.

Documents and script ​

  • HTML parsing with inline, external, defer, and async classic scripts
  • Module scripts, import maps, and dynamic import()
  • document.write during parsing
  • External style sheets and native CSS parsing with a browser-owned CSSOM
  • Image loading without a decoder: complete, currentSrc, naturalWidth/naturalHeight, the load and error events, srcset/sizes/<picture> selection, and img.decode(), all from the container header
  • Emulated viewport, media type, and supported preferences such as colour scheme, reduced motion, contrast, and pointer capabilities in both matchMedia and stylesheet @media rules
  • about:blank, data:text/html, direct content, and HTTP(S) navigation
  • Custom elements, shadow DOM, templates, ranges, traversal, selection, DOMParser, and XMLSerializer
  • Geometry Interfaces: DOMPoint, DOMRect, DOMQuad and DOMMatrix with their read-only parents and WebKitCSSMatrix, including transform-list strings; layout answers such as getBoundingClientRect are DOMRect instances
  • CSS Font Loading: FontFace from a src string or a buffer, with its descriptors parsed and serialized, load() fetching url() sources in order, and document.fonts as a set-like FontFaceSet with check(), load(), ready and the loading/loadingdone/loadingerror events
  • Web Animations: document.timeline, DocumentTimeline, Animation, KeyframeEffect, element.animate() and element/document getAnimations(), with frame-driven playback, timing and easing calculations, ready/finished promises, playback events, replacement/persistence, and discrete commitStyles()
  • The HTML Sanitizer API: Sanitizer, setHTML/setHTMLUnsafe, getHTML and Document.parseHTML/parseHTMLUnsafe, including declarative shadow roots (sanitizing runs after parsing, see the DOM divergences)

Canvas (non-rendering) ​

  • HTMLCanvasElement.getContext('2d') and OffscreenCanvas.getContext('2d') return stable, per-canvas contexts. Other supported context modes return null; no renderer or GPU is involved.
  • Drawing state, validated colors/styles and line dashes, save/restore/reset, and 2D transforms with independent DOMMatrix results. Assigning width or height resets the drawing state and save stack, including same-value and content-attribute writes.
  • Path2D, gradients, patterns, the 2D path/drawing operations, and approximate TextMetrics let scripts prepare charts without rasterization.
  • Real ImageData with Uint8ClampedArray storage; canvas reads return transparent-black data and writes validate without retaining pixels.
  • Valid transparent PNG data URLs and asynchronous PNG Blob results from toBlob and offscreen convertToBlob. See Limitations for text heuristics, encoding/allocation limits and deliberate no-rendering behavior.

SVG DOM (non-rendering) ​

  • SVG 2 element brands and prototype chains for roots, groups, basic shapes, text, gradients, patterns, clips, masks, markers, images, links, scripts, views and filters. Unknown SVG names remain SVGElement; names are case-sensitive.
  • Live animated attributes, lengths, angles, numbers, rectangles, aspect ratios, points and transform lists. Base-value edits serialize into content attributes; retained objects observe attribute changes. Animated values mirror the base values through read-only objects, without SMIL.
  • SVG list inspection and mutation methods, constants on both interface objects and prototypes, root value factories, and SVGMatrix/SVGPoint/SVGRect aliases of the Geometry interfaces.
  • Attribute-derived basic-shape bounding boxes, lengths and points along outlines, plus ancestor-transform getCTM/getScreenCTM. See Limitations for the synthetic geometry and text policies.

Runtime ​

  • Timers, promises, microtasks, animation-frame callbacks, and postMessage
  • fetch, XMLHttpRequest, WebSocket, EventSource, blobs, and FileReader
  • Forms, validation, history, location, cookies, local/session storage
  • IndexedDB databases, transactions, indexes and cursors, shared by same-origin pages and dedicated workers within a context, including plain HTTP. In-memory data survives navigation; BrowserOptions.MaxIndexedDbBytes limits committed storage to 50 MiB per origin by default. An additional BrowserOptions.MaxTotalStorageBytes budget defaults to 100 MiB per context across origins, pages and workers, counting committed IndexedDB plus built-in localStorage and live Cache Storage; BrowserContextOptions.MaxTotalStorageBytes can override it. Custom local/cache partitions, session storage, cookies, empty partition maps and peak allocations are excluded. See IndexedDB.
  • Origin-partitioned caches in secure contexts (HTTPS and HTTP loopback/localhost), shared by a context's pages and dedicated workers and retained across same-origin navigations. The default in-memory partition enforces BrowserOptions.MaxCacheStorageBytes per origin (5 MiB); custom StoragePartitionProvider.GetCacheStorage implementations can persist or refuse storage.
  • Resource Timing for completed fetch/XHR bodies, scripts/modules, stylesheets/CSS imports, images, frame documents, and explicit font/media loads. Entries support PerformanceObserver, buffered replay, the 250-entry resource buffer, resizing, clearing, and resourcetimingbufferfull.
  • Navigation Timing for top-level documents, including fetch/body and DOM/load milestones, navigation type and same-origin redirect counts. Same-document navigations keep the existing entry.
  • window.open and anchor/area/form targets open or reuse pages in the same context, including form POST bodies, window names, noopener/noreferrer, opener relationships, script closing and cross-page structured-cloned postMessage. Remote WindowProxy objects support the cross-origin window/location surface; see the isolation limits below.
  • Navigation API: lazy window.navigation, history entries with stable keys/IDs and independently structured-cloned state, navigate/reload/traversal result promises, SPA interception, transitions and activation. Native history/location changes, anchors, forms and CDP history traversals share the page's session history and navigation events; cross-document loads preserve same-origin contiguous entries. Host Page.NavigateAsync/ReloadAsync and CDP Page.navigate/Page.reload are browser-UI navigations: as in HTML they fire no navigate event and a page cannot intercept or cancel them, but a script navigation before they commit still aborts them.
  • Cookie Store: window.cookieStore with promise-based get, getAll, set, delete, onchange and CookieChangeEvent, sharing the context jar with document.cookie, network responses and CDP
  • Dedicated module workers and classic/module SharedWorker, including entangled MessagePort connections, onconnect, classic importScripts, and context-scoped sharing by constructor origin, script URL and name. See Workers for lifetime and limits.
  • Mutation, intersection, and resize observers, with documented no-layout semantics
  • Constructible event interfaces beyond UI Events: ToggleEvent (fired by <dialog> and <details>), CommandEvent, AnimationEvent, TransitionEvent, GamepadEvent, DragEvent, StorageEvent, TouchEvent and the device events, plus the legacy TextEvent through document.createEvent; ClipboardEvent is absent
  • The navigator's system state: HTML's compatibility constants, empty plugins/mimeTypes, userAgentData (UA Client Hints, following a CDP userAgentMetadata override), permissions.query, storage.estimate, registerProtocolHandler argument validation, Notification, screen/screen.orientation and visualViewport following the emulated viewport — see Limitations for what they answer

Automation and reading ​

  • CSS selectors and accessibility-snapshot ref= targets
  • Click, focus, typing, key presses, select controls, form submission, and virtual scrolling
  • Markdown, text, serialized HTML, and accessibility snapshots
  • Request, console, page-error, response, and dialog inspection
  • Page.Popup announces registered popups off the page loop, and Page.Opener exposes their opener. Popups join BrowserContext.Pages and CDP target discovery/attachment, with openerId when an opener exists.
  • CDP connections for supported Puppeteer and Playwright operations

Feature support is intentionally narrower than a graphical browser. Check Limitations before depending on layout, frames, media, or full client compatibility.