Detect a finger swipe through JavaScript on the iPhone and Android

Simple vanilla JS example for horizontal swipe:

let touchstartX = 0
let touchendX = 0
    
function checkDirection() {
  if (touchendX < touchstartX) alert('swiped left!')
  if (touchendX > touchstartX) alert('swiped right!')
}

document.addEventListener('touchstart', e => {
  touchstartX = e.changedTouches[0].screenX
})

document.addEventListener('touchend', e => {
  touchendX = e.changedTouches[0].screenX
  checkDirection()
})

You can use pretty same logic for vertical swipe.


I merged a few of the answers here into a script that uses CustomEvent to fire swiped events in the DOM. Add the 0.7k swiped-events.min.js script to your page and listen for swiped events:

swiped

document.addEventListener('swiped', function(e) {
    console.log(e.target); // the element that was swiped
    console.log(e.detail.dir); // swiped direction
});

swiped-left

document.addEventListener('swiped-left', function(e) {
    console.log(e.target); // the element that was swiped
});

swiped-right

document.addEventListener('swiped-right', function(e) {
    console.log(e.target); // the element that was swiped
});

swiped-up

document.addEventListener('swiped-up', function(e) {
    console.log(e.target); // the element that was swiped
});

swiped-down

document.addEventListener('swiped-down', function(e) {
    console.log(e.target); // the element that was swiped
});

You can also attach directly to an element:

document.getElementById('myBox').addEventListener('swiped-down', function(e) {
    console.log(e.target); // the element that was swiped
});

Optional config

You can specify the following attributes to tweak how swipe interaction functions in your page (these are optional).

<div data-swipe-threshold="10"
     data-swipe-timeout="1000"
     data-swipe-ignore="false">
      Swiper, get swiping!
</div>

To set defaults application wide, set config attributes on topmost element:

<body data-swipe-threshold="100" data-swipe-timeout="250">
    <div>Swipe me</div>
    <div>or me</div>
</body>

Source code is available on Github


Simple vanilla JS code sample:

document.addEventListener('touchstart', handleTouchStart, false);        
document.addEventListener('touchmove', handleTouchMove, false);

var xDown = null;                                                        
var yDown = null;

function getTouches(evt) {
  return evt.touches ||             // browser API
         evt.originalEvent.touches; // jQuery
}                                                     
                                                                         
function handleTouchStart(evt) {
    const firstTouch = getTouches(evt)[0];                                      
    xDown = firstTouch.clientX;                                      
    yDown = firstTouch.clientY;                                      
};                                                
                                                                         
function handleTouchMove(evt) {
    if ( ! xDown || ! yDown ) {
        return;
    }

    var xUp = evt.touches[0].clientX;                                    
    var yUp = evt.touches[0].clientY;

    var xDiff = xDown - xUp;
    var yDiff = yDown - yUp;
                                                                         
    if ( Math.abs( xDiff ) > Math.abs( yDiff ) ) {/*most significant*/
        if ( xDiff > 0 ) {
            /* right swipe */ 
        } else {
            /* left swipe */
        }                       
    } else {
        if ( yDiff > 0 ) {
            /* down swipe */ 
        } else { 
            /* up swipe */
        }                                                                 
    }
    /* reset values */
    xDown = null;
    yDown = null;                                             
};

Tested in Android.

Tags:

Javascript

Iphone

Android

Swipe

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