# touch_support

> Maximum touch points, whether a TouchEvent can be created and whether ontouchstart exists, in one short value.

Source: https://whiskerjs.com/signals/touch-support/ (last updated 2026-10-26)

**touch_support at a glance (from the library code, signalsVersion 9)**

| Field | Value |
| --- | --- |
| Component name | `touch_support` |
| In the visitorId | yes |
| structuredId group | [device (screen, memory, CPU)](https://whiskerjs.com/docs/identifiers/#structuredid) |
| Hashing | plain value; a digest only when longer than 128 characters or not printable ASCII |
| Excluded under | no browser class |
| Inner timeout | 1000 ms |
| Added in | [signalsVersion 1](https://whiskerjs.com/whats-new/) |

> **In plain words:**
>
> Touch screens report how many fingers they can track at once, and browsers on touch devices offer touch events to pages. WhiskerJS writes down three simple facts about this. A desktop usually says no touch at all, a phone says five or more touch points and touch events, and touch laptops are somewhere in between.

## What it reads

- `navigator.maxTouchPoints` (or the old `msMaxTouchPoints`), 0 when missing;
- whether `document.createEvent('TouchEvent')` succeeds (1) or throws (0);
- whether `ontouchstart` exists on the window (1 or 0).

The value is `points=<n>,event=<0|1>,start=<0|1>`.

## How the technique works

Each part is read in its own guard, so a missing property or a throwing call only sets that part to 0. Together they describe the input hardware and how the browser exposes it, which separates more cases than any part alone: desktop browsers, touch laptops, tablets that present a desktop user agent, and phones.

## Why it helps

It splits device classes cheaply and is a useful consistency check for your server: a phone user agent with `points=0,event=0,start=0`, or a desktop platform with ten touch points, is unusual. It is in the `device` group.

## Stability

Stable for a given device and browser. It can change when a touch screen or pen tablet is attached, when a browser’s device emulation is switched on in developer tools, or with a browser update that changes which touch APIs are exposed.

## Browser support and what blocks it

`ok` in all browsers; not in the exclusion table. Typical values: `points=0,event=0,start=0` on desktops, `points=5,event=1,start=1` on phones. See [Chrome on Android](https://whiskerjs.com/browsers/chrome-android/), [Safari and every iOS browser](https://whiskerjs.com/browsers/safari-ios/) and [Samsung Internet](https://whiskerjs.com/browsers/samsung-internet/) for touch devices.

## Privacy

Three coarse facts about touch input. No permission, no prompt, no request; no touch event is listened to or dispatched.

## How WhiskerJS handles noise and failures

| Status | ruleId | When |
| --- | --- | --- |
| `ok` | none | always, in practice |
| `blocked` | `security_error`, `threw` | only if something outside the guards throws (not expected) |
| `excluded` | `caller_excluded` | your `exclude` list |
| `timed_out` | `timeout`, `aborted` | 1000 ms inner timeout, budget, abort |

## Example value

From the headless test browsers in a container: `points=0,event=0,start=0` (Chromium and Firefox) and `points=0,event=1,start=0` (WebKit).

```json
"touch_support": { "status": "ok", "value": "points=5,event=1,start=1", "hashed": false }
```

## Questions and answers

### Why does a desktop sometimes show event=1?

Some browsers let pages create a TouchEvent even without a touch screen; the headless WebKit test browser used for these pages did. That is why WhiskerJS reports three separate parts instead of one yes or no.

### Can touch_support fail?

Practically not. Each part has a safe default of 0, so the component is almost always ok. It can only be excluded by you or time out.

## Related pages

- [screen_resolution](https://whiskerjs.com/signals/screen-resolution/): The screen size.
- [platform](https://whiskerjs.com/signals/platform/): navigator.platform.
- [ua_client_hints](https://whiskerjs.com/signals/ua-client-hints/): The mobile flag in Chromium.
- [Safari and every iOS browser](https://whiskerjs.com/browsers/safari-ios/): Touch devices on WebKit.