Swipe JS for Mobile App

swipe.js

/**
 * @name _swipe
 * Small event handler for swipe in mobile phones using javascript, this handler is based on http://stackoverflow.com/a/27115070
 * This handler supports classes, ids and elements.
 * @author David Aguilar
 * @example
 *
 * _swipe("#element", function(dir, elem) {
 *     console.info("You're swiping to %s direction.", dir.type);
 * });
 *
 * _swipe("#anotherElement", function(dir, elem) {
 *     if (dir.type === "up") {
 *         // do something
 *     }
 * });
 *
 */

var _swipe = function(element, fn) {
    var swipe = {
            sX: 0,
            sY: 0,
            eX: 0,
            eY: 0
        },
        minX = 20,
        maxX = 40,
        minY = 40,
        maxY = 50,
        direction = null,
        eventType = {
            'up': {type: 'up', event: 'evt:swipe:up'},
            'down': {type: 'down', event: 'evt:swipe:down'},
            'left': {type: 'left', event: 'evt:swipe:left'},
            'right': {type: 'right', event: 'evt:swipe:right'}
        };

    function getSelector(ele) {
        var chars = {
            'id': '#',
            'class': '.'
        };

        if (ele.indexOf(chars.id) > -1) {
            return document.getElementById(ele.substr(1));
        } else if (ele.indexOf(chars.class) > -1) {
            return document.getElementsByClassName(ele.substr(1));
        } else {
            return document.getElementsByTagName(ele);
        }
    }

    function touchStartHandler (evt) {
        var touches = evt.touches[0];
        swipe.sX = touches.screenX;
        swipe.sY = touches.screenY;
    }

    function touchMoveHandler (evt) {
        evt.preventDefault();
        var touches = evt.touches[0];
        swipe.eX = touches.screenX;
        swipe.eY = touches.screenY;
    }

    function touchEndHandler (evt) {
        if (isHorizontal()) {
            direction = swipe.eX > swipe.sX ? eventType.right : eventType.left;
        } else {
            direction = swipe.eY < swipe.sY ? eventType.up : eventType.down;
        }

        if (direction && typeof fn === 'function') {
            fn(direction, element, evt);
            return true;
        }
    }

    function isHorizontal () {
        var checkX = swipe.eX - minX > swipe.sX || swipe.eX + minX < swipe.sX,
            checkY = swipe.eY < swipe.sY + maxY && swipe.sY > swipe.eY - maxY;

        return checkX && checkY;
    }

    function isVertical () {
        var checkY = swipe.eY - minY > swipe.sY || swipe.eY + minY < swipe.sY,
            checkX = swipe.eX < swipe.sX + maxX && swipe.sX > swipe.eX - maxX;

        return checkX && checkY;
    }

    function init (el) {
        if (!el) {
            console.warn('Coudn\'t be able to set listener to undefined element');
            return;
        }

        el.addEventListener('touchstart', touchStartHandler, false);
        el.addEventListener('touchmove', touchMoveHandler, false);
        el.addEventListener('touchend', touchEndHandler, false);
    }

    init(getSelector(element));
};