Test touch events
Multitouch visualization with live touch points, contact radius, and force readings. Drag fingers across the surface to see start/move/end events logged in real time.
Testing multitouch
Touch events fire touchstart, touchmove, touchend, touchcancel. Each touch has id, position, radius, and force. Multitouch needs touchAction: none.
- 01
Single touch
Tap once — see start/end events with id 0.
Inputs are treated as UTF-8 throughout the pipeline and validated client-side as you type — nothing dispatches until the value is well-formed.
startinpututf-8client-sidevalidatedtype · texttouchstart · set#0 (120, 80)
loaded · parsedclient-side - 02
Multitouch
Two or three fingers — distinct ids and colors.
Each toggle re-computes through a memoised hook, so flipping options never resets your input and the UI stays snappy on large inputs.
multioptionslivememoisedtogglesactive · memoised3 · live#0 #1 #2
options set · memoisedlive - 03
Drag
touchmove fires continuously while sliding.
Randomness — where used — comes from
crypto.getRandomValues, neverMath.random. Heavy work sits inuseMemo.movecomputeinstantlocaldeterministicevents · instantstream · computedtouchmove × N
computed · instantinstant - 04
Read radius/force
radiusX/Y describe contact size; force where supported.
Copy writes through
navigator.clipboardand downloads use aBlob— zero network traffic. Same input plus same options always yield the same bytes.pressurecopydownloadzero-networkreproducibleok · copiedrich · copiedr=20×20 f=0.45
shipped · ready to shipsuccess
Pro tips for everyday utilities
Reach for crypto.getRandomValues
Cryptographically random for IDs, tokens, salts. Math.random is for animation and games, not security.
Mock data with seeds
Faker-style libraries can be seeded so tests are reproducible. Embed the seed in the fixture file.
Reference cards beat memory
Cheatsheets for Vim, Git, Docker, Linux signals are faster than man pages when you’re mid-flow.
Browser APIs vary
Touch events, gamepads, and clipboard differ across vendors. Feature-detect before use.
Persist in the right place
localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data.
When to test touch
Mobile QA, gesture libs, drawing apps.
Mobile QA
Confirm gestures fire on real hardware. Random values come from crypto.getRandomValues — cryptographically secure for tokens, salts, and session IDs. Math.random is deterministic enough for animations but predictable enough to be a security bug.
CSPRNG-backedGesture libs
Verify Hammer.js or your custom recognizer. Pair with hashids, ULID, or UUID v7 when you need both random and sortable — useful for primary keys, public-facing IDs, and event log ordering without a sequence column.
reproducibleDrawing apps
Tune brush size from radius+force. Output is deterministic given the same seed, so fixtures and tests stay reproducible across CI runs and contributor machines. Embed the seed in the fixture file for full replay.
snappyPWA testing
Sanity-check touch handlers in production builds. Heavy work runs through useMemo so the UI stays snappy on large inputs. Same input + same options yields identical bytes — the kind of stability snapshot tests rely on.
feature-detectedAccessibility
Validate touch targets are big enough. Storage tools persist to the right backend: localStorage for user preferences, sessionStorage for transient state, IndexedDB for structured data. Pick the right shelf and quota worries disappear.
a11yCross-device
iPhone vs Android touch fidelity comparison. Browser feature detection: clipboard, fullscreen, gamepad, and Web Bluetooth APIs gracefully fall back when unavailable. No surprise white screens on Safari or older Firefox.
production-readyFrequently asked questions
Something missing?
Tell us what you need. We ship the top requests every two weeks.