JS关闭窗口时产生的事件及用法示例

/************ 关闭窗口，提交评价 **************/
window.onbeforeunload = function(){
   var pageWidth = Math.max(window.top.document.body.scrollWidth, window.top.document.documentElement.scrollWidth);
   var pageHeight = Math.max(window.top.document.body.scrollHeight, window.top.document.documentElement.scrollHeight);
   var cltHeight = Math.max(window.top.document.body.clientHeight, window.top.document.documentElement.clientHeight);
   var width = 400 ;
   var height = 200 ;
   var layer = window.top.document.getElementById("zz_layer");
   if (layer != null) {
   layer.parentNode.removeChild(layer);
   }
   // 遮罩层
 var layer= window.top.document.createElement("div");
 layer.id = "zz_layer";
 layer.style.filter = "alpha(opacity=38)";//ie
 layer.style.opacity = "0.38";//ff
 layer.style.width = pageWidth + "px";
 layer.style.height = pageHeight + "px";
 layer.style.position= "absolute";
 layer.style.top = 0;
 layer.style.left = 0;
 layer.style.backgroundColor = "#000";
 layer.style.zIndex = "9998";
 window.top.document.body.appendChild(layer);
 // 评价窗口
 var newbox = document.getElementById("KF_PJ_DIV");
 newbox.style.zIndex = "9999";
 newbox.style.display = "block";
 newbox.style.width = width + "px";
 newbox.style.height = height + "px";
 newbox.style.border = "#565656 4px solid";
 newbox.style.background = "#FFFFFF";
 newbox.style.position = "absolute";
 newbox.style.left = pageWidth/2 + "px";
 newbox.style.top = (cltHeight/2) + "px";
 if(height/2 > (cltHeight/2)){
  newbox.style.marginTop = ( - (cltHeight/2)) + "px";
 }else{
  newbox.style.marginTop = ( - height/2) + "px";
 }
 if(width/2 > (pageWidth/2)){
  newbox.style.marginLeft = ( - (pageWidth/2)) + "px";
 }else{
  newbox.style.marginLeft = ( - width/2) + "px";
 }
   return "您尚未对客服服务作出评价，请点击‘取消'评分！";
  };
  function mydiv_resize(){
  var pageWidth = Math.max(window.top.document.body.scrollWidth, window.top.document.documentElement.scrollWidth);
   var pageHeight = Math.max(window.top.document.body.scrollHeight, window.top.document.documentElement.scrollHeight);
   var cltHeight = Math.max(window.top.document.body.clientHeight, window.top.document.documentElement.clientHeight);
   var cltWidth = Math.max(window.top.document.body.clientWidth, window.top.document.documentElement.clientWidth);
   var width = 400 ;
   var height = 200 ;
  var layer = window.top.document.getElementById("zz_layer");
   if (layer != null) {
   // 遮罩层
  layer.style.width = pageWidth + "px";
  layer.style.height = pageHeight + "px";
   }
 // 评价窗口
 var newbox = document.getElementById("KF_PJ_DIV");
 newbox.style.left = cltWidth/2 + "px";
 newbox.style.top = (cltHeight/2) + "px";
 if(height/2 > (cltHeight/2)){
  newbox.style.marginTop = ( - (cltHeight/2)) + "px";
 }else{
  newbox.style.marginTop = ( - height/2) + "px";
 }
 if(width/2 > (pageWidth/2)){
  newbox.style.marginLeft = ( - (pageWidth/2)) + "px";
 }else{
  newbox.style.marginLeft = ( - width/2) + "px";
 }
}
window.onresize = mydiv_resize;