Knowledge documents in Browser.
Browsers split even simultaneous input into separate keydown events, which causes the bug where pressing keys together only goes one direction. This explains how to fix it with a short, bounded collection window and fixed-step consumption
Why DOM-coordinate highlights break on the next visit, and how quote, context, and position selectors with weighted scoring and confidence thresholds fix it
How to safely connect extension execution contexts that cannot share memory with message APIs, runtime validation, handler routing, response envelopes, and change notifications
Why blur or Enter can commit a half-composed Korean character, and how to fix it with composition state rather than assumptions about event order
To show a native-app-like loading splash from the first paint while hiding it from crawlers, inject the node with an inline blocking script at the top of body — not with SSR markup or UA branching. Why a UA gate breaks the static cache
When LCP is slow but the image is tiny and TBT is near zero, the bottleneck is not download — it's that the LCP element is a client component, so hydration blocks the paint. Diagnosis and a server-ify prescription
The intermittent broken images caused by creating a createObjectURL in useMemo and revoking it in useEffect, and the pattern of rendering server-proxied images directly by URL to eliminate the race at its source
Applying an offline-shell fallback to every request returns HTML on image/API failures, breaking <img> and polluting the cache. Apply the shell fallback only to document requests whose request.mode is navigate
CSS duration reset alone does not disable JS spring or Observer-based page transitions; explicitly gate with matchMedia
A generation pattern that blocks late-finishing requests from re-writing cache when async deletion overlaps stale-while-revalidate
A pattern to stabilize Canvas 2D graph node color and twinkle via ID hash, and restore globalAlpha and shadow state
SWR pattern in Service Worker Cache Storage: return cache immediately and refresh in the background, with capacity and security caveats
A pattern for building scroll-entry fade/slide with animation-timeline view() and animation-range entry, without JS
A typography strategy that uses the optional display to prevent late webfont swap and reduce tag/body layout shift (CLS)
pointercancel, touch-action, and coarse-pointer hover fallbacks to stabilize custom drag·resize on mobile
React commit attaches child DOM first, so an ancestor ref may be null at the time of a child useLayoutEffect — defer ancestor DOM side effects to useEffect
Why a popover/toolbar pinned with coordinates measured only once to a position:fixed anchor drifts off the text after scrolling, and the scroll/resize re-measurement pattern
Why a text-selection-based floating toolbar is driven by selectionchange instead of a mousedown/mouseup gate, and the ownership pattern for hybrid editors
A pattern for explicitly delegating to document undo via chainCommands when a rich-text engine preventDefaults Mod-Z/Y during focus
The principle of preventing composition breakage in a CJK IME composition session with contenteditable/React editors via commit defer and mount-once
A browser-native drag session API that implements moves crossing subtree boundaries via the OS drag loop and DataTransfer
user-select:none only blocks drag selection and does not fully exclude text from the Selection/clipboard; to exclude it, CSS generated content is safer
Why CLS occurs when a loading skeleton occupies different space than the final UI, and the height/width reservation prescription to prevent it
An experiment design that avoids dev-server trace outliers and compares before/after with an N-run median
How to distinguish that the Lighthouse Performance score, category audits, and Chrome trace ms are each different instrumentations
The stages a browser goes through from receiving HTML/CSS/JS to painting the first screen pixels, and how to shorten that path