function sAlert(str){
var msgw,msgh,bordercolor;
msgw=300;//提示窗口的宽度



msgh=150;//提示窗口的高度



titleheight=25//提示窗口标题高度
bordercolor="#0A84C1";//提示窗口的边框颜色



titlecolor="#60AFD7";//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 或使用 screen.width//屏幕的宽度



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） //动态创建元素，这里创建的是 div
//定义div属性，即相当于(相当于，但确不是，必须对对象属性进行定义

 

//<div id="bgDiv" style="position:absolute; top:0; background-color:#777; filter:progid:DXImagesTransform.Microsoft.Alpha(style=3,opacity=25,finishOpacity=75); opacity:0.6; left:0; width:918px; height:768px; z-index:10000;"></div>
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 = "1000";
bgObj.style.className="alert_progress";
document.getElementById('mainbody').appendChild(bgObj);//在body内添加该div对象

//创建一个div对象（提示框层）
var msgObj=document.createElement("div")
//定义div属性，即相当于
//<div id="msgDivOnBgDiv" 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;"></div>
msgObj.setAttribute("id","msgDivOnBgDiv");
msgObj.setAttribute("align","center");
msgObj.style.background="white";
msgObj.style.border="1px solid " + bordercolor;
msgObj.style.position = "absolute";
msgObj.style.left = "60%";
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 = "10003";
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</h4>
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 " + bordercolor;
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
//<input type="button" align="center" style="width:100px; align:center; margin-left:250px; margin-bottom:10px;" value="关闭">
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 "+ bordercolor;
button.style.color="white";
button.onclick=removeObj;

function removeObj(){//点击标题栏触发的事件
    document.getElementById('mainbody').removeChild(bgObj);//删除背景层Div
    document.getElementById("msgDivOnBgDiv").removeChild(title);//删除提示框的标题栏



    document.getElementById('mainbody').removeChild(msgObj);//删除提示框层
}
document.getElementById('mainbody').appendChild(msgObj);//在body内添加提示框div对象msgObj
document.getElementById("msgDivOnBgDiv").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
//<p style="margin:1em 0;" id="msgTxt">测试效果</p>
txt.style.margin="1em 0"
txt.setAttribute("id","msgTxt");
if(!str){
	txt.innerHTML="<font color='#3B5786'>畅途网正在为您查询航班信息，请稍候！</font><br/><img src='/images/flying.gif'/>";//来源于函数调用时的参数值
}else{
	txt.innerHTML=str;
}


document.getElementById("msgDivOnBgDiv").appendChild(txt);//在提示框div中添加提示信息对象txt
//document.getElementById("msgDivOnBgDiv").appendChild(button);//在提示框div中添加按钮对象button
return true;
}