Device

Platform info, the current display size, and the host resize event. device is a plain global object — nothing to construct.

At a glance

if (device.platform === 'ios') toast('running on iOS')

const layout = (w: number, h: number) => {
  console.log('display is', w, 'x', h, 'logical px')
}
layout(device.width, device.height)               // readable any time
device.addEventListener('resize', layout)         // and again on every resize

Platform info

device.platform     // "web" | "android" | "ios" | string  (read-only)
device.language     // host language code, e.g. "en"       (read-only)
device.pixelRatio   // physical px per logical px; 1 on standard displays, 2–3 on retina/iOS

pixelRatio is the ratio to bake a Canvas at for crisp output without hardcoding: new Canvas(w, h, { pixelRatio: device.pixelRatio }). It falls back to 1 if the host doesn't report one.

Display size

device.width        // current display width, logical px  (read-only)
device.height       // current display height, logical px (read-only)

The same values the resize event delivers, but readable at any time — not only inside the listener. Both are logical px (like clientX/clientY), never physical pixels.

resize event

device.addEventListener('resize', (width, height) => { })   // logical px
device.removeEventListener('resize', callback)              // same function reference

Fires whenever the host viewport changes (rotation, window resize). The only channel device emits; other channel names are ignored.

Precise touch

device.setPreciseTouch(enabled: boolean)    // OFF by default

Opt into the precise-touch system where the platform supports it. When on, fast strokes are sampled at the touch digitizer's full rate (iOS coalesced touches, ≈120–240 Hz) instead of once per display frame (~60 Hz) — a pointer-heavy app (drawing, handwriting, dragging) gets more points and smoother lines. Leave it off for tap/button UIs.

See also

• Pointer events & gestures — the events precise touch feeds
• Conventions — logical px, the addEventListener pattern