回到顶端js实现
function goTop(){ var _btn = document.getElementById("goTop"); if (document.documentElement && document.documentElement.scrollTop) { var _con = document.documentElement; } else if (document.body) { var _con = document.body; } window.onscroll = set; _btn.style.left = "125px"; _btn.onclick = function() { _btn.style.display = "none"; window.onscroll = null; this.timer = setInterval(function() { _con.scrollTop -= Math.ceil(_con.scrollTop * 0.3); if (_con.scrollTop == 0) { clearInterval(_btn.timer, window.onscroll = set); } }, 10); }; function set() { _btn.style.display = _con.scrollTop ? 'block': "none"; } }; document.write("<div id=\"goTop\" style=\"font-size:12px; width:20px; height:55px; background:#0950A2; color:#fff; line-height:14px; position:fixed; bottom:30px; display:none; cursor:pointer; text-align:center; padding:5px 0; z-index:1; _position:absolute; _top:expression(eval(document.compatMode && document.compatMode == \'CSS1Compat\') ? documentElement.scrollTop + (documentElement.clientHeight - this.clientHeight) - 30 : document.body.scrollTop + (document.body.clientHeight - this.clientHeight) - 30);\">返回顶部</div>"); window.onscroll = goTop;
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