/*
Use two event listeners.
Assume mouse input initially and bind a touchstart event listener to the document.
On touchstart, add a mousemove event listener to listen for two consecutive mousemove events firing within 20ms, using performance.now().
Run the callback with the input type as an argument in either of these situations.
*/
const onUserInputChange = callback => {
let type = 'mouse',
lastTime = 0;
const mousemoveHandler = () => {
const now = performance.now();
if (now - lastTime < 20)
(type = 'mouse'), callback(type), document.removeEventListener('mousemove', mousemoveHandler);
lastTime = now;
};
document.addEventListener('touchstart', () => {
if (type === 'touch') return;
(type = 'touch'), callback(type), document.addEventListener('mousemove', mousemoveHandler);
});
};
/* example:
onUserInputChange(type => {
console.log('The user is now using', type, 'as an input method.');
});
*/