1: Let’s take a look at using css first. You need to write expressions in css, but it flashes and flashes. Assign the variable "ignoreMe", and "document.documentElement.scrollTop? document.documentElement.scrollTop: document.body.scrollTop" (this is a bug in IE).
1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> 2 <HTML> 3 <HEAD> 4 <TITLE> css test </TITLE> 5 <style> 6 #LoadingStatus{ 7 position:fixed !important; 8 position:absolute; 9 top:100px;10 top: expression( ( 100 + ( ignoreMe = document.documentElement.scrollTop ? document.documentElement.scrollTop : document.body.scrollTop ) ) + 'px' );11 margin:0 0 0 -110px;12 width:220px;height:19px;13 left:50%;14 text-align:center;15 border:1px solid red;16 }17 </style>18 </HEAD>19 <BODY>20 <div id="LoadingStatus" style="display:none;"> loading...</div>21 <div style="height:1024px">22 <input type="button" onclick="document.getElementById('LoadingStatus').style.display=''" value='显示loading' />23 </div> 24 <div>25 <input type="button" onclick="document.getElementById('LoadingStatus').style.display=''" value='显示loading' />26 </div>27 </BODY>28 </HTML>2: Written in JS, it can actually be applied to css. It is no different from the above. It should be noted that under FF, the upper left and upper right are still floating. Under IE, everything is fixed, but flickering. Which should be used with caution.
1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 2 <HTML> 3 <HEAD> 4 <TITLE>JAVASCRIPT</TITLE> 5 <META HTTP-EQUIV="Content-Type" CONTENT="text/html" charset="UTF-8"> 6 </HEAD> 7 <style> 8 <!-- 9 .div {10 position: absolute;11 border: 2px solid red;12 background-color: #EFEFEF;13 line-height:90px;14 font-size:12px;15 z-index:1000;16 }17 -->18 </style>19 <BODY>20 <div id="Javascript.Div1" class="div" style="width: 240px; height:90px" align="center">正中...</div>21 <SCRIPT LANGUAGE="JavaScript">22 function sc1(){23 document.getElementById("Javascript.Div1").style.top=24 document.documentElement.scrollTop+(document.documentElement.clientHeight-document.getElementById("Javascript.Div1").offsetHeight)/2+"px"25 document.getElementById("Javascript.Div1").style.left=26 document.documentElement.scrollLeft+(document.documentElement.clientWidth-document.getElementById("Javascript.Div1").offsetWidth)/2+"px";27 }28 </SCRIPT>29 <div id="Javascript.Div2" class="div" style="width: 240px; height:90px;" align="center">左上...</div>30 <SCRIPT LANGUAGE="JavaScript">31 function sc2(){32 document.getElementById("Javascript.Div2").style.top=document.documentElement.scrollTop;33 document.getElementById("Javascript.Div2").style.left=document.documentElement.scrollLeft;34 }35 </SCRIPT>36 <div id="Javascript.Div3" class="div" style="width: 240px; height:90px;" align="center">左下...</div>37 <SCRIPT LANGUAGE="JavaScript">38 function sc3(){39 document.getElementById("Javascript.Div3").style.top=40 document.documentElement.scrollTop+document.documentElement.clientHeight-document.getElementById("Javascript.Div3").offsetHeight+"px";41 document.getElementById("Javascript.Div3").style.left=document.documentElement.scrollLeft;42 }43 </SCRIPT>44 <div id="Javascript.Div4" class="div" style="width: 240px; height:90px;" align="center">右上...</div>45 <SCRIPT LANGUAGE="JavaScript">46 function sc4(){47 document.getElementById("Javascript.Div4").style.top=document.documentElement.scrollTop;48 document.getElementById("Javascript.Div4").style.left=49 document.documentElement.scrollLeft+document.documentElement.clientWidth-document.getElementById("Javascript.Div4").offsetWidth+"px";50 }51 </SCRIPT>52 <div id="Javascript.Div5" class="div" style="width: 240px; height:90px;" align="center">右下...</div>53 <SCRIPT LANGUAGE="JavaScript">54 function sc5(){55 56 document.getElementById("Javascript.Div5").style.top=57 document.documentElement.scrollTop+document.documentElement.clientHeight-document.getElementById("Javascript.Div5").offsetHeight+"px";58 document.getElementById("Javascript.Div5").style.left=59 document.documentElement.scrollLeft+document.documentElement.clientWidth-document.getElementById("Javascript.Div5").offsetWidth+"px";60 }61 </SCRIPT>62 <SCRIPT LANGUAGE="JavaScript">63 <!--64 function scall(){65 sc1();sc2();sc3();sc4();sc5();66 }67 window.onscroll=scall;68 window.onresize=scall;69 window.onload=scall;70 //-->71 </SCRIPT>72 <div style="position: absolute; top: 0; left: 0; width: 10000px; height: 4000px;"></div>73 </BODY>74 </HTML>3: This is still written in js, but it will not flash during the scrolling process of the IE browser. The compatibility effect is very good.
1 <!DOCTYPE HTML> 2 <html> 3 <head> 4 <meta http-equiv="content-type" charset="utf-8" /> 5 <title>Js跟随滚动条移动的DIV</title> 6 </head> 7 <style type="text/css"> 8 *{margin:0;padding: 0;background-color:#000; } 9 div#con{width: 800px;margin: 0 auto;}10 div.pop{width:800px;font-size: 18px;background:yellow;padding:20px 0;margin:20px auto;border:1px solid yellow;text-align: center;color: #000;}11 p{width:800px;padding:20px 0;background:#fff;border:1px solid #000;margin:20px auto;text-align: center;}12 div.active{position: fixed;top: 100px;z-index: 100;margin: 0;_position: absolute;}13 </style>14 <body>15 <div id="con" style="height:2000px;">16 <p>我是元素p</p>17 <div id="myDiv" class="pop active">18 我是随屏幕滚动的DIV，我距离顶部高度适中为100px，修改css就可以修改该值19 </div>20 21 <p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p>我是元素p</p><p style="color:red;position:fixed;top:400px;">我是元素top:400px;看是否支持固定定位</p>22 </div>23 <script type="text/javascript">24 (function(){25 //if(navigator.userAgent.toLocaleLowerCase().indexOf('msie 6.0;')>1){26 if(checkFixed()){27 return ;28 }//只需对不支持固定定位的浏览器做处理29 30 //将下面需要使用的dom相关操作在scrollDiv外面提取一次，避免多次dom操作31 var fixedObj = document.getElementById("myDiv"),32 height = fixedObj.offsetHeight,//标签高度提前读取出来33 firstTop =getTop(fixedObj),//记录页面一开始标签所在位置34 timer;35 window.onscroll = function(){//这里做个延时执行，可以减少scroll执行频率36 clearTimeout(timer);37 timer = setTimeout(function(){38 scrollDiv()39 },30);40 }41 42 function scrollDiv(){43 var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;44 fixedObj.style.top=(firstTop+scrollTop)+'px';45 }46 //获取元素在页面里top值47 function getTop(obj) {48 var top = 0;49 while(obj){50 top += obj.offsetTop;51 obj = obj.offsetParent;52 }53 return top;54 }55 //判断浏览器是否支持固定定位56 function checkFixed(){57 var o = document.createElement('div'),58 body = document.getElementsByTagName('body')[0],59 fig = false;60 body.insertBefore( o, body.firstChild );61 o.style.cssText ='position:fixed;top:20px;margin:0;padding:0;border:none;width:0px;height:0px;';62 fig = o.offsetTop==20;63 body.removeChild(o);64 return fig;65 }66 })()67 </script>68 </body>69 </html>
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
