JS 判断用户在触摸屏上的滑动方向

[Dream4ever]

实现过程

Google：js touch up down。

参考方案：Detect a finger swipe through JavaScript on the iPhone and Android。

代码：

let touchstartX = 0
let touchendX = 0

const slider = document.getElementById('slider')

function handleGesture() {
  if (touchendX < touchstartX) alert('swiped left!')
  if (touchendX > touchstartX) alert('swiped right!')
}

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

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