 myScroll = new iScroll('wrapper', {
  vScrollbar: false,
  useTransition: true,
  topOffset: pullDownOffset,
  onRefresh: function () {
   if (pullDownEl.className.match('loading')) {
    pullDownEl.className = '';
    pullDownEl.querySelector('.pullDownLabel').innerHTML = 'Pull down to refresh...';
   } else if (pullUpEl.className.match('loading')) {
    pullUpEl.className = '';
    pullUpEl.querySelector('.pullUpLabel').innerHTML = 'Pull up to load more...';
   }
  },
  onScrollMove: function () {
   if (this.y > 5 && !pullDownEl.className.match('flip')) {
    pullDownEl.className = 'flip';
    pullDownEl.querySelector('.pullDownLabel').innerHTML = 'Release to refresh...';
    this.minScrollY = 0;
   } else if (this.y < 5 && pullDownEl.className.match('flip')) {
    pullDownEl.className = '';
    pullDownEl.querySelector('.pullDownLabel').innerHTML = 'Pull down to refresh...';
    this.minScrollY = -pullDownOffset;
   } else if (this.y < (this.maxScrollY - 5) && !pullUpEl.className.match('flip')) {
    pullUpEl.className = 'flip';
    pullUpEl.querySelector('.pullUpLabel').innerHTML = 'Release to refresh...';
    this.maxScrollY = this.maxScrollY;
   } else if (this.y > (this.maxScrollY + 5) && pullUpEl.className.match('flip')) {
    pullUpEl.className = '';
    pullUpEl.querySelector('.pullUpLabel').innerHTML = 'Pull up to load more...';
    this.maxScrollY = pullUpOffset;
   }
  },
  onScrollEnd: function () {
   if (pullDownEl.className.match('flip')) {
    pullDownEl.className = 'loading';
    pullDownEl.querySelector('.pullDownLabel').innerHTML = 'Loading...';
    pullDownAction();
   } else if (pullUpEl.className.match('flip')) {
    pullUpEl.className = 'loading';
    pullUpEl.querySelector('.pullUpLabel').innerHTML = 'Loading...';
    pullUpAction();
   }
  }
 });

頁面無法彈回的原因在于：手指劃出屏幕后touchend事件無法觸發(fā)，回彈動畫就無法執(zhí)行。解決辦法就是：當手指接近屏幕邊緣的時候，手動觸發(fā)動畫方法。

在onScrollMove方法中插入判斷代碼：

  onScrollMove: function () {
   if((this.y < this.maxScrollY) && (this.pointY < 1)){
    this.scrollTo(0, this.maxScrollY, 400);
    return;
   } else if (this.y > 0 && (this.pointY > window.innerHeight - 1)) {
    this.scrollTo(0, 0, 400);
    return;
   }

   ......
  }

下面解釋一下這段代碼的意思。

this.y是頁面已經滾動的垂直距離，this.maxScrollY是最大垂直滾動距離，this.pointY手指當前的垂直坐標。

當this.y < this.maxScrollY，就是已經處于上拉的過程，當(this.y < this.maxScrollY) && (this.pointY < 1)時，處于上拉且手指已經觸及屏幕邊緣，這時候手動觸發(fā)this.scrollTo(0, this.maxScrollY, 400)，頁面就開始回彈。

下拉過程也可以同理分析。

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