引入iscroll-probe.js        https://download.csdn.net/my

<div class="wrap">
        <div class="content">
            454545
        </div>
        <div class="dropdown">
            下拉重新整理
        </div>
    </div>

        let iscroll = new IScroll('.wrap',{probeType:3})
        let dropdown = document.querySelector('.dropdown')
        iscroll.on('scrollStart',function () {
            iscroll.endTime=0
            iscroll.on('scroll',fnScroll)
        })
        function fnScroll(){
            if(iscroll.endTime==0){  // 正在拖動
                if(iscroll.y>100){
                    dropdown.innerHTML='請鬆手'
                }else {
                    dropdown.innerHTML='下拉重新整理'
                }
            }else {  // 鬆手了
                iscroll.off('scroll',fnScroll)
                dropdown.innerHTML='載入中...'
                iscroll.scrollTo(0,30)
            }
        }