Simple and short swipe direction detection in vanilla js

swipe.js

var last={x: null,y: null};
document.addEventListener("touchstart", e => {
	let touch = e.touches[0];
	last.x = touch.clientX;
	last.y = touch.clientY;
});
document.addEventListener("touchend", e => {
	let touch = e.changedTouches[0];
	let diff = {x:last.x-touch.clientX,y:last.y-touch.clientY};
	if (Math.abs(diff.x) > Math.abs(diff.y)) {
		if (diff.x > 0) {
			// left
		} else {
			// right
		}
	} else {
		if (diff.y > 0) {
			// up
		} else {
			// down
		}
	}
});