点击页面上的按纽，弹出一个层，背景变灰
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title></title><script>function sAlert(str) {var msgw, msgh, bordercolor;msgw = 400;//提示窗口的宽度 msgh = 100;//提示窗口的高度 titleheight = 25 //提示窗口标题高度 bordercolor = "#336699 ";//提示窗口的边框颜色 titlecolor = "#99CCFF ";//提示窗口的标题颜色 var sWidth, sHeight;sWidth = document.body.offsetWidth;//浏览器工作区域内页面宽度 sHeight = screen.height;//屏幕高度（垂直分辨率） //背景层（大小与窗口有效区域相同，即当弹出对话框时，背景显示为放射状透明灰色） var bgObj = document.createElement("div ");//创建一个div对象（背景层） //定义div属性，即相当于 // <div id= "msgDiv " align= "center " style= "background-color:white; border:1px solid #336699; position:absolute; left:50%; top:50%; font:12px/1.6em Verdana,Geneva,Arial,Helvetica,sans-serif; margin-left:-225px; margin-top:npx; width:400px; height:100px; text-align:center; line-height:25px; z-index:100001; "> __tag_35$351_bgObj.setAttribute('id ', 'bgDiv ');bgObj.style.position = "absolute";bgObj.style.top = "0";bgObj.style.background = "#777 ";bgObj.style.filter = "progid:DXImageTransform.Microsoft.Alpha(style=3,opacity=25,finishOpacity=75 ";bgObj.style.opacity = "0.6";bgObj.style.left = "0";bgObj.style.width = sWidth + "px";bgObj.style.height = sHeight + "px";bgObj.style.zIndex = "10000";document.body.appendChild(bgObj);//在body内添加该div对象 var msgObj = document.createElement("div")//创建一个div对象（提示框层） //定义div属性，即相当于 // <div id= "msgDiv " align= "center " style= "background-color:white; border:1px solid #336699; position:absolute; left:50%; top:50%; font:12px/1.6em Verdana,Geneva,Arial,Helvetica,sans-serif; margin-left:-225px; margin-top:npx; width:400px; height:100px; text-align:center; line-height:25px; z-index:100001; "> __tag_72$353_ msgObj.setAttribute("id", "msgDiv");msgObj.setAttribute("align", "center");msgObj.style.background = "white ";msgObj.style.border = "1px solid ";msgObj.style.position = "absolute";msgObj.style.left = "50%";msgObj.style.top = "50%";msgObj.style.font = "12px/1.6em Verdana, Geneva, Arial, Helvetica, sans-serif";msgObj.style.marginLeft = "-225px";msgObj.style.marginTop = -75 + document.documentElement.scrollTop+ "px";msgObj.style.width = msgw + "px";msgObj.style.height = msgh + "px";msgObj.style.textAlign = "center";msgObj.style.lineHeight = "25px";msgObj.style.zIndex = "10001";var title = document.createElement("h4");//创建一个h4对象（提示框标题栏） //定义h4的属性，即相当于 // <h4 id= "msgTitle " align= "right " style= "margin:0; padding:3px; background-color:#336699; filter:progid:DXImageTransform.Microsoft.Alpha(startX=20, startY=20, finishX=100, finishY=100,style=1,opacity=75,finishOpacity=100); opacity:0.75; border:1px solid #336699; height:18px; font:12px Verdana,Geneva,Arial,Helvetica,sans-serif; color:white; cursor:pointer; " onclick= " "> 关闭 __tag_110$425_ title.setAttribute("id", "msgTitle");title.setAttribute("align", "right");title.style.margin = "0";title.style.padding = "3px";title.style.background = bordercolor;title.style.filter = "progid:DXImageTransform.Microsoft.Alpha(startX=20, startY=20, finishX=100, finishY=100,style=1,opacity=75,finishOpacity=100);";title.style.opacity = "0.75 ";title.style.border = "1px solid";title.style.height = "18px ";title.style.font = "12px Verdana, Geneva, Arial, Helvetica, sans-serif";title.style.color = "white";title.style.cursor = "pointer";title.innerHTML = "关闭";title.onclick = removeObj;var button = document.createElement("input");//创建一个input对象（提示框按钮） //定义input的属性，即相当于 // __tag_146$7_ button.setAttribute("type", "button");button.setAttribute("value", "关闭");button.style.width = "60px";button.style.align = "center";button.style.marginLeft = "250px";button.style.marginBottom = "10px";button.style.background = bordercolor;button.style.border = "1px solid";button.style.color = "white";button.onclick = removeObj;function removeObj(){//点击标题栏触发的事件 document.body.removeChild(bgObj);//删除背景层Div document.getElementById("msgDiv").removeChild(title);//删除提示框的标题栏 document.body.removeChild(msgObj);//删除提示框层 }document.body.appendChild(msgObj);//在body内添加提示框div对象msgObj document.getElementById("msgDiv").appendChild(title);//在提示框div中添加标题栏对象title var txt = document.createElement("p");//创建一个p对象（提示框提示信息） //定义p的属性，即相当于 // __tag_192$7_ 测试效果 __tag_192$60_ txt.style.margin = "1em 0"txt.setAttribute("id ", "msgTxt");txt.innerHTML = str;//来源于函数调用时的参数值 document.getElementById("msgDiv").appendChild(txt);//在提示框div中添加提示信息对象txt document.getElementById("msgDiv").appendChild(button);//在提示框div中添加按钮对象button</script><meta http-equiv="Content-Type " content="text/html; charset=utf8 " /></head><body><p>测试弹出框</p><input type="button" onclick=" sAlert( '测试效果 <br/> 嗯！效果还不错！ '); " value="点击这里 " /></body></html>?