js隐藏与显示回到顶部按钮

window.onscroll = function () {
    if (document.documentElement.scrollTop + document.body.scrollTop > 100) {
        document.getElementById("scrollto").style.display = "block";
    }
    else {
        document.getElementById("scrollto").style.display = "none";
    }
}


原文https://www.cnblogs.com/youring2/archive/2012/11/21/2780315.html