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;