上拉加载

// 滚动事件触发
window.addEventListener('scroll',()=> {
    if(this.getScrollTop() + this.getClientHeight()+50> this.getScrollHeight()) {
        console.log('下拉刷新了')
        //此处发起AJAX请求
    }
})

// 下拉加载  获取滚动条当前的位置
getScrollTop() {
    let scrollTop = 0;
    if(document.documentElement && document.documentElement.scrollTop) {
        scrollTop = document.documentElement.scrollTop;
    } else if(document.body) {
        scrollTop = document.body.scrollTop;
    }
    return scrollTop;
}
//获取当前可视范围的高度
getClientHeight() {
    var clientHeight = 0;
    if(document.body.clientHeight && document.documentElement.clientHeight) {
        clientHeight = Math.min(document.body.clientHeight, document.documentElement.clientHeight);
    } else {
        clientHeight = Math.max(document.body.clientHeight, document.documentElement.clientHeight);
    }
    return clientHeight;
}
//获取文档完整的高度
getScrollHeight() {
    return Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
}