Javascript swipe and tap events handling

I couldn't provide any solution for my problem which is following: I am developing a site in which I would like to handle swipe events on mobile devices. I use this piece of JS code:

function swipedetect(el, callback){

var touchsurface = el,
swipedir,
startX,
startY,
distX,
distY,
threshold = 150, //required min distance traveled to be considered swipe
restraint = 100, // maximum distance allowed at the same time in perpendicular direction
allowedTime = 300, // maximum time allowed to travel that distance
elapsedTime,
startTime,
handleswipe = callback || function(swipedir){}

touchsurface.addEventListener('touchstart', function(e){
    var touchobj = e.changedTouches[0]
    swipedir = 'none'
    dist = 0
    startX = touchobj.pageX
    startY = touchobj.pageY
    startTime = new Date().getTime() // record time when finger first makes contact with surface
    e.preventDefault()
}, false)

touchsurface.addEventListener('touchmove', function(e){
    e.preventDefault() // prevent scrolling when inside DIV
}, false)

touchsurface.addEventListener('touchend', function(e){
    var touchobj = e.changedTouches[0]
    distX = touchobj.pageX - startX // get horizontal dist traveled by finger while in contact with surface
    distY = touchobj.pageY - startY // get vertical dist traveled by finger while in contact with surface
    elapsedTime = new Date().getTime() - startTime // get time elapsed
    if (elapsedTime <= allowedTime){ // first condition for awipe met
        if (Math.abs(distX) >= threshold && Math.abs(distY) <= restraint){ // 2nd condition for horizontal swipe met
            swipedir = (distX < 0)? 'left' : 'right' // if dist traveled is negative, it indicates left swipe
        }
        else if (Math.abs(distY) >= threshold && Math.abs(distX) <= restraint){ // 2nd condition for vertical swipe met
            swipedir = (distY < 0)? 'up' : 'down' // if dist traveled is negative, it indicates up swipe
        }
    }
    handleswipe(swipedir)
    e.preventDefault()
}, false)
}

//USAGE:
/*
var el = document.getElementById('someel')
swipedetect(el, function(swipedir){
     swipedir contains either "none", "left", "right", "top", or "down"
     if (swipedir =='left')
        alert('You just swiped left!')
})

I am using this function to detect swipes on whole document and I have a problem with distinguishing tap and swipe event. For example: I have a button and I can't press it on mobile device because this event is handled by swipe detection function. How can I modify it (or do some other tricks) to detect ONLY swipes on my whole page?