id为自增项,怎样用alert弹出当前的id

id为自增项,怎样用alert弹出当前的id

function salert(str){<br>   var msgw,msgh,bordercolor;<br>   msgw=400;//提示窗口的宽度<br>   msgh=100;//提示窗口的高度<br>   titleheight=25 //提示窗口标题高度<br>   bordercolor="#336699";//提示窗口的边框颜色<br>   titlecolor="#99ccff";//提示窗口的标题颜色<br><br>   var swidth,sheight;<br>   swidth=document.body.offsetwidth;<br>   sheight=document.body.offsetheight;<br>   if (sheight<screen.height)<br>   {<br>    sheight=screen.height;<br>   }<br><br>var bgobj=document.createelement("div");<br>   bgobj.setattribute('id','bgdiv');<br>   bgobj.style.position="absolute";<br>   bgobj.style.top="0";<br>   bgobj.style.background="#777";<br>   bgobj.style.filter="progid:dximagetransform.microsoft.alpha(style=3,opacity=25,finishopacity=75";<br>   bgobj.style.opacity="0.6";<br>   bgobj.style.left="0";<br>   bgobj.style.width=swidth + "px";<br>   bgobj.style.height=sheight + "px";<br>   bgobj.style.zindex = "10000";<br>   document.body.appendchild(bgobj);<br><br>   var msgobj=document.createelement("div")<br>   msgobj.setattribute("id","msgdiv");<br>   msgobj.setattribute("align","center");<br>   msgobj.style.background="white";<br>   msgobj.style.border="1px solid " + bordercolor;<br>    msgobj.style.position = "absolute";<br>    msgobj.style.left = "50%";<br>    msgobj.style.top = "50%";<br>    msgobj.style.font="12px/1.6em verdana, geneva, arial, helvetica, sans-serif";<br>    msgobj.style.marginleft = "-225px" ;<br>    msgobj.style.margintop = -75+document.documentelement.scrolltop+"px";<br>    msgobj.style.width = msgw + "px";<br>    msgobj.style.height =msgh + "px";<br>    msgobj.style.textalign = "center";<br>    msgobj.style.lineheight = (msgh-titleheight) + "px";<br>    msgobj.style.zindex = "10001";<br><br>    var title=document.createelement("h4");<br>    title.setattribute("id","msgtitle");<br>    title.setattribute("align","right");<br>    title.style.margin="0";<br>    title.style.padding="3px";<br>    title.style.background=bordercolor;<br>    title.style.filter="progid:dximagetransform.microsoft.alpha(startx=20, starty=20, finishx=100, finishy=100,style=1,opacity=75,finishopacity=100);";<br>    title.style.opacity="0.75";<br>    title.style.border="1px solid " + bordercolor;<br>    title.style.height="18px";<br>    title.style.font="12px verdana, geneva, arial, helvetica, sans-serif";<br>    title.style.color="white";<br>    title.style.cursor="pointer";<br>    title.innerhtml="关闭";<br>    title.onclick=function(){<br>    document.body.removechild(bgobj);<br>    document.getelementbyid("msgdiv").removechild(title);<br>    document.body.removechild(msgobj);<br>    }<br>    document.body.appendchild(msgobj);<br>    document.getelementbyid("msgdiv").appendchild(title);<br>    var txt=document.createelement("p");<br>    txt.style.margin="1em 0"<br>    txt.setattribute("id","msgtxt");<br>    txt.innerhtml=str;<br>    document.getelementbyid("msgdiv").appendchild(txt);<br>    }<br>//调用方法

不明白啊 = =！