如果要在 Pageable 捲動的時候判斷目前是在哪邊，可以用內建的方法來抓，其內建的方法有：
onst pages = new Pageable("#container");
pages.on("init", data => {
// do something when the instance is ready
});
pages.on("update", data => {
// do something when the instance is updated
// this event also fires when the screen size changes
});
pages.on("scroll.before", data => {
// do something before scrolling starts
// this event will fire when the defined delay begins
// e.g. if the delay is set to 400, this event will
// fire 400ms BEFORE the "scroll.start" event fires
});
pages.on("scroll.start", data => {
// do something when scrolling starts
// this event will fire when the defined delay ends
// e.g. if the delay is set to 400, this event will
// fire 400ms AFTER the "scroll.before" event fires
});
pages.on("scroll", data => {
// do something during scroll
});
pages.on("scroll.end", data => {
// do something when scrolling ends
});
所以說如果我要知道捲動結束後的點，就可以抓 scroll.end 這個事件， console.log(data)後會抓到類似這樣的內容：
{index: 1, percent: 99.81222222222222, scrolled: 421.2075777777778, max: 422}
所以要知道是在第幾個，就抓 data.index 就好了，index 是從 0 開始的。
