On-screen keyboard detector

Detects the presence of the on-screen keyboard (OSK) shown by mobile browsers when the user interacts with input controls on a webpage.

Background

This approach employs the browsers layout and visual viewports (Article on MDN, Demo) to observe the appearance of the virtual keyboard.

At the time of writing on

• Mobile Safari the keyboard is excluded from the visual viewport, while on
• Chrome for Android the keyboard is excluded from both the visual and the layout viewport.

Chrome's behaviour makes it necessary to also observe focusin, focusout, resize and visibilitychange events.

Limitations

• On Chrome for Android the keyboard must be initially hidden when subscribing to the detector.
• On Chrome for Android the hidden and visible events are dispatched with a approximate 1 second delay.
• On iOS requires Safari v. ≥ 13
• On iPad the predictive text bar, which is shown when an external keyboard is used, is not detected as visible keyboard.

Install

npm install on-screen-keyboard-detector

Usage

Basic

import { subscribe } from 'on-screen-keyboard-detector';

const unsubscribe = subscribe(visibility => {
	if (visibility === "hidden"){
		// ...
	}
	else { // visibility === "visible"
		// ...
	}
});

// After calling unsubscribe() the callback will no longer be invoked.
unsubscribe();

API

subscribe(listenerCallback): unsubscribe

Begins to observe browser events and invokes the provided callback function when a change in the keyboard visibility is detected.

Parameter	Type	Description
callback	function(String)	user-defined handler which receives the keyboard visibility changes

Return value

function(): void : Unsubscribes to receive updates

isSupported()

Returns true if the browser runtime supports oskd.

Advanced Usage

Multiple Subscriptions (PubSub)

PubSub is not part of this module and needs additional tools, e.g. emittery. See demo/pubsub.html

import {subscribe} from 'on-screen-keyboard-detector';
import Emitter from 'emittery';

const emitter = new Emitter();

subscribe(visibility => emitter.emit(visibility));

emitter.on('hidden', function() { /* ... */ });
emitter.on('visible', function() { /* ... */ });

Tests

Requirements (not listed in package.json)

• mocha ☕
• chai 🍵
• selenium-webdriver
• a Mac for Mobile Safari tests
• running a local webserver (see TEST_SERVER in package.json), E.g. run http-server in the project root folder http-server . --port 8081

Android

For real devices make sure

• the adb server is running (adb start-server), and
• a device is connected via USB or Wifi (adb devices -l)
• ggf. adb tcpip 5555 and adb connect <test phone ip address> (see "setup_test" in package.json) Then run npm run test:chrome.

iOS

Connect a device where Remote Automatation is enabled for Safari (see the Webkit blog). Then run npm run test:ios

iOS tests should be performed manually (see the demo folder), because Webdriver controlled Mobile Safari does not show the virtual keyboard

Dependencies

Ramda, and Most for the reactive functional infrastructure.

Changelog

v2.2.0

• isSupported() requires touch enabled screen
• Support for Safari on iPad

v2.1.0

• project is now an ES module