本文实例讲述了JavaScript实现弹出DIV层同时页面背景渐变成半透明效果。分享给大家供大家参考，具体如下：
<!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>JavaScript弹出DIV层，页面背景渐变成半透明</title> <style> html,body{font-size:12px;margin:0px;height:100%;} .mesWindow{border:#666 1px solid;background:#fff;} .mesWindowTop{border-bottom:#eee 1px solid;margin-left:4px;padding:3px;font-weight:bold;text-align:left;font-size:12px;} .mesWindowContent{margin:4px;font-size:12px;} .mesWindow .close{height:15px;width:28px;border:none;cursor:pointer;text-decoration:underline;background:#fff} </style> <script> var isIe=(document.all)?true:false; //设置select的可见状态 function setSelectState(state) { var objl=document.getElementsByTagName('select'); for(var i=0;i<objl.length;i++) { objl[i].style.visibility=state; } } function mousePosition(ev) { if(ev.pageX || ev.pageY) { return {x:ev.pageX, y:ev.pageY}; } return { x:ev.clientX + document.body.scrollLeft - document.body.clientLeft,y:ev.clientY + document.body.scrollTop - document.body.clientTop }; } //弹出方法 function showMessageBox(wTitle,content,pos,wWidth) { closeWindow(); var bWidth=parseInt(document.documentElement.scrollWidth); var bHeight=parseInt(document.documentElement.scrollHeight); if(isIe){ setSelectState('hidden');} var back=document.createElement("div"); back.id="back"; var styleStr="top:0px;left:0px;position:absolute;background:#666;width:"+bWidth+"px;height:"+bHeight+"px;"; styleStr+=(isIe)"filter:alpha(opacity=0);":"opacity:0;"; back.style.cssText=styleStr; document.body.appendChild(back); showBackground(back,50); var mesW=document.createElement("div"); mesW.id="mesWindow"; mesW.className="mesWindow"; mesW.innerHTML="<div><table width='100%' height='100%'><tr><td>"+wTitle+"</td><td><input type='button' onclick='closeWindow();' title='关闭窗口' value='关闭' /></td></tr></table></div><div id='mesWindowContent'>"+content+"</div><div></div>"; styleStr="left:"+(((pos.x-wWidth)>0)?(pos.x-wWidth):pos.x)+"px;top:"+(pos.y)+"px;position:absolute;width:"+wWidth+"px;"; mesW.style.cssText=styleStr; document.body.appendChild(mesW); } //让背景渐渐变暗 function showBackground(obj,endInt) { if(isIe) { obj.filters.alpha.opacity+=1; if(obj.filters.alpha.opacity<endInt) { setTimeout(function(){showBackground(obj,endInt)},5); } }else{ var al=parseFloat(obj.style.opacity);al+=0.01; obj.style.opacity=al; if(al<(endInt/100)) {setTimeout(function(){showBackground(obj,endInt)},5);} } } //关闭窗口 function closeWindow() { if(document.getElementById('back')!=null) { document.getElementById('back').parentNode.removeChild(document.getElementById('back')); } if(document.getElementById('mesWindow')!=null) { document.getElementById('mesWindow').parentNode.removeChild(document.getElementById('mesWindow')); } if(isIe){ setSelectState('');} } //测试弹出 function testMessageBox(ev) { var objPos = mousePosition(ev); messContent="<div>消息正文</div>"; showMessageBox('窗口标题',messContent,objPos,350); } </script> </head> <body> <div> <div;><a href="#none">弹出窗口</a></div> <div;><select ID="Select1" NAME="Select1"><option>下拉</option></select>弹出窗口时会将其隐藏，关闭时会让其显示，目的是在IE中防止弹出的DIV挡不住下拉框</div> <div;><a href="#none">弹出窗口</a></div> <div;><a href="#none">弹出窗口</a></div> </div> <br /> </body> </html>
希望本文所述对大家JavaScript程序设计有所帮助。