version 1 of siwper

swiper.js

/**
 * Swiper module
 *
 * It performs the callback function and returns the swipe direction
 */
class Swiper {

	constructor() {
		// minimal swiping minDistance
		this.minDistance = 100;

		// required min time allowed to travel that distance
		this.minTime = 99;

		// maximum time allowed to travel that distance to avoid really slow swiping
		this.maxTime = 250;
	}

	init(element, callback, preventScroll = false) {
		this.elem = element;
		this.preventScroll = preventScroll;
		this.callback = callback;
		this.configureSwipe();
	}

	configureSwipe() {
		let startX,
			startY,
			distance,
			elapsedTime,
			startTime;

		this.elem.addEventListener('touchstart', (e) => {
			let changedTouch = e.changedTouches[0];

			distance = 0;
			startTime = new Date().getTime();
			startX = changedTouch.pageX;
			startY = changedTouch.pageY;


			if (this.preventScroll) {
				e.preventDefault();
			}
		}, false);

		if (this.preventScroll) {
			this.elem.addEventListener('touchmove', (e) => {
				e.preventDefault();
			}, false);
		}

		this.elem.addEventListener('touchend', (e) => {
			let changedTouch = e.changedTouches[0];
			let swipeDirection = Swiper.STATUS.NO_SWIPE;

			distance = changedTouch.pageX - startX;
			elapsedTime = new Date().getTime() - startTime;

			// Check for the validity of whether or not an actual swipe occurred
			// before going into the direction details.
			if (this.validateSwipe(elapsedTime, startY, changedTouch.pageY)) {
				swipeDirection = this.getSwipeDirection(distance);
			}

			this.callback(swipeDirection);

			if (this.preventScroll) {
				e.preventDefault();
			}
		}, false)

	}

	getSwipeDirection(distance) {
		const STATUS = Swiper.STATUS;

		if (distance >= this.minDistance) {
			return STATUS.SWIPE_RIGHT;
		} else if (distance < ( this.minDistance * -1)) {
			return STATUS.SWIPE_LEFT;
		}

		return status.TOO_SHORT;
	}

	validateSwipe(elapsedTime, pageY, startY) {
		return elapsedTime <= this.maxTime && elapsedTime > this.minTime && Math.abs(pageY - startY) <= 100;
	}

	static isLeftSwipe(direction) {
		return direction === Swiper.STATUS.SWIPE_LEFT;
	}

	static isRightSwipe(direction) {
		return direction === Swiper.STATUS.SWIPE_RIGHT;
	}


	static get STATUS() {
		return {
			SWIPE_LEFT: 'SWIPE_LEFT',
			SWIPE_RIGHT: 'SWIPE_RIGHT',
			NO_SWIPE: 'NO_SWIPE',
			TOO_SHORT: 'TOO_SHORT'
		};
	}
}

module.exports = Swiper;