enable swipe using javascript

1document.addEventListener('touchstart', handleTouchStart, false);        
2document.addEventListener('touchmove', handleTouchMove, false);
3
4var xDown = null;                                                        
5var yDown = null;
6
7function getTouches(evt) {
8  return evt.touches ||             // browser API
9         evt.originalEvent.touches; // jQuery
10}                                                     
11
12function handleTouchStart(evt) {
13    const firstTouch = getTouches(evt)[0];                                      
14    xDown = firstTouch.clientX;                                      
15    yDown = firstTouch.clientY;                                      
16};                                                
17
18function handleTouchMove(evt) {
19    if ( ! xDown || ! yDown ) {
20        return;
21    }
22
23    var xUp = evt.touches[0].clientX;                                    
24    var yUp = evt.touches[0].clientY;
25
26    var xDiff = xDown - xUp;
27    var yDiff = yDown - yUp;
28
29    if ( Math.abs( xDiff ) > Math.abs( yDiff ) ) {/*most significant*/
30        if ( xDiff > 0 ) {
31            /* left swipe */ 
32        } else {
33            /* right swipe */
34        }                       
35    } else {
36        if ( yDiff > 0 ) {
37            /* up swipe */ 
38        } else { 
39            /* down swipe */
40        }                                                                 
41    }
42    /* reset values */
43    xDown = null;
44    yDown = null;                                             
45};