模态窗口，js、学习提高用 狼

    <script type="text/javascript" language="javascript">

            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;
                sHeight = screen.height;
                var bgObj = document.createElement("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.width =900 + "px";
                bgObj.style.height ="100%";
                bgObj.style.zIndex = "10000";
                document.body.appendChild(bgObj);

                var msgObj = document.createElement("div")
                msgObj.setAttribute("id", "msgDiv");
                msgObj.setAttribute("align", "center");
                msgObj.style.background = "white";
                msgObj.style.border = "1px solid " + bordercolor;
                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");
                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 = "";
                title.onclick = function() {
//                    document.body.removeChild(bgObj);
//                    document.getElementById("msgDiv").removeChild(title);
//                    document.body.removeChild(msgObj);
                }
                document.body.appendChild(msgObj);
                document.getElementById("msgDiv").appendChild(title);
                var txt = document.createElement("p");
                txt.style.margin = "1em 0"
                txt.setAttribute("id", "msgTxt");
                txt.innerHTML = str;
                document.getElementById("msgDiv").appendChild(txt);
            }
   </script>