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

Question

I need to detect and react to left/right-swipes, but want to give the user the ability to scroll on the same element, so as long as he moves his finger only left/right with

Answer 1

There is a "bug" in the accepted answer. If you don't use Chrome on Android but the build in browser or a "webview" (For a html5-hybrid-app) for example, then the swipe is not being detected.

I found out that the event doesn't fire, because of the normal scroll behavior. So adding "e.preventDefault();" in touchmove would fix it or the fix from Eric Fuller in the accepted answer.

It's a nice snipped but in a mobile WebApp or Website this could result in a bad scroll stuttering, because the touch-events are observed the whole time.

So I decided to build something new. It's not as comfortable like to have new event listeners, but it's comfortable enough for my needs and it's performat.

function detectswipe(el,func) {
  swipe_det = new Object();
  swipe_det.sX = 0;
  swipe_det.sY = 0;
  swipe_det.eX = 0;
  swipe_det.eY = 0;
  var min_x = 20;  //min x swipe for horizontal swipe
  var max_x = 40;  //max x difference for vertical swipe
  var min_y = 40;  //min y swipe for vertical swipe
  var max_y = 50;  //max y difference for horizontal swipe
  var direc = "";
  ele = document.getElementById(el);
  ele.addEventListener('touchstart',function(e){
    var t = e.touches[0];
    swipe_det.sX = t.screenX; 
    swipe_det.sY = t.screenY;
  },false);
  ele.addEventListener('touchmove',function(e){
    e.preventDefault();
    var t = e.touches[0];
    swipe_det.eX = t.screenX; 
    swipe_det.eY = t.screenY;    
  },false);
  ele.addEventListener('touchend',function(e){
    //horizontal detection
    if ((((swipe_det.eX - min_x > swipe_det.sX) || (swipe_det.eX + min_x < swipe_det.sX)) && ((swipe_det.eY < swipe_det.sY + max_y) && (swipe_det.sY > swipe_det.eY - max_y)))) {
      if(swipe_det.eX > swipe_det.sX) direc = "r";
      else direc = "l";
    }
    //vertical detection
    if ((((swipe_det.eY - min_y > swipe_det.sY) || (swipe_det.eY + min_y < swipe_det.sY)) && ((swipe_det.eX < swipe_det.sX + max_x) && (swipe_det.sX > swipe_det.eX - max_x)))) {
      if(swipe_det.eY > swipe_det.sY) direc = "d";
      else direc = "u";
    }

    if (direc != "") {
      if(typeof func == 'function') func(el,direc);
    }
    direc = "";
  },false);  
}

myfunction(el,d) {
  alert("you swiped on element with id '"+el+"' to "+d+" direction");
}

To use the function just use it like

detectswipe('an_element_id',myfunction);

detectswipe('an_other_element_id',my_other_function);

If a swipe is detected the function "myfunction" is called with parameter element-id and "l,r,u,d" (left,right,up,down).

Example: http://jsfiddle.net/rvuayqeo/1/