Detect left/right-swipe on touch-devices, but allow up/down-scrolling

swipedirection.js

// a modification from http://goo.gl/tLbLXr

var attachEvent = function(element, event, fn) {
    if (element.addEventListener)
        element.addEventListener(event, fn, false);
    else if (element.attachEvent) // if IE
        element.attachEvent('on' + event, fn);
}

var onReady = function(func) {
    if (document.readyState == 'complete') {
        func();
    } else {
        attachEvent(window, 'load', func);
    }
}

onReady(function(){
  (function(d){
    var ce=function(e,n){var a=document.createEvent("CustomEvent");a.initCustomEvent(n,true,true,e.target);e.target.dispatchEvent(a);a=null;return false},
      nm=true,sp={x:0,y:0},ep={x:0,y:0},
      touch={
        touchstart:function(e){sp={x:e.touches[0].pageX,y:e.touches[0].pageY}},
        touchmove:function(e){nm=false;ep={x:e.touches[0].pageX,y:e.touches[0].pageY}},
        touchend:function(e){if(nm){ce(e,'fc')}else{var x=ep.x-sp.x,xr=Math.abs(x),y=ep.y-sp.y,yr=Math.abs(y);if(Math.max(xr,yr)>20){ce(e,(xr>yr?(x<0?'SwipeLeft':'SwipeRight'):(y<0?'SwipeUp':'SwipeDown')))}};nm=true},
        touchcancel:function(e){nm=false}
      };
    for(var a in touch){d.addEventListener(a,touch[a],false);}
  })(document);  
});

/* Usage: 
    document.body.addEventListener('SwipeLeft', function(){
        history.go(-1);
    }, false);

*/