Mobile touch move detection

handleTouchMove.js

let touches = {
  touchstart: Object.assign({}, {
    x: -1,
    y: -1
  }),
  touchmove: Object.assign({}, {
    x: -1,
    y: -1
  })
}

function handleTouch (evt) {
  if (typeof evt.touches === 'undefined') {
    return 
  }

  let touch = evt.touches[0]
  switch (evt.type) {
    case 'touchstart':
    case 'touchmove':
      touches[evt.type].x = touch.pageX
      touches[evt.type].y = touch.pageY
      break

    case 'touchend': {
      if (touches.touchstart.x > -1 && touches.touchmove.x > -1) {
        let dx = touches.touchmove.x - touches.touchstart.x,
            dy = touches.touchmove.y - touches.touchstart.y

        if (Math.abs(dx) > Math.abs(dy)) {
          // Horizontal move
          if (dx > 0) {
            // Move right
          }
          else {
            // Move left
          }
        }
        else {
          // Vertical move
          if (dy > 0) {
            // Move down
          }
          else {
            // Move up
          }
        }
      }
      break
    }
  }
}

document.addEventListener('touchstart', handleTouch)
document.addEventListener('touchmove', handleTouch)
document.addEventListener('touchend', handleTouch)