这个背景图片为什么不能显示？

源码如下：
<html>
<head>
<title>日历</title>
</head>
<script language="Javascript">
<!--
  var currentdate, currentday, currentyear, currentmonth, xday;
  
  function dayinfo()
  { var today = new Date();
    
currentdate=today.getDate();
currentday=today.getDay();
currentmonth=today.getMonth();
currentyear=today.getYear();
var tempday= currentdate%7;
xday=(currentday + 7 - tempday) % 7 + 1;
  }
  
  function displaycalender()
  { var alldays=new Array(31,28,31,30,31,30,31,31,30,31,30,31);
    var weekdayname=new Array("Sun","Mon","Tue","Wed","Thu","Fri","Sat");
var monthname=new Array("January","February","March","April","May","June",
        "July","August","September","October","November","December");
    var filename;

dayinfo();

if (currentyear%4==0) allday[1]++;

if (currentmonth<=2&&currentmonth>=11) {filename="w1.jpg";}
else if (currentmonth<=5&&currentmonth>=2) {filename="sp1.jpg";}
else if (currentmonth<=8&&currentmonth>=5) {filename="su1.jpg";}
else if (currentmonth<=11&&currentmonth>=8){filename="f1.jpg";}

document.writeln("<TABLE BORDER=0 STYLE='background-image:url(''+filename+'')'>");
document.writeln("<TR>");

document.writeln("<CAPTION STYLE='font-family:''+''comic sansms''+'';color:blue'>");
document.writeln(currentyear+' '+monthname[currentmonth]);
document.writeln("</CAPTION>");

document.writeln("<TR>");
  for (i=0;i<7;i++)
  document.writeln("<TH STYLE='color:red'>"+weekdayname[i]+"</TH>");
document.writeln("</TR>");

  for (i=1;i<=alldays[currentmonth]+xday;i++)
    { if (i%7==1) document.writeln("<TR>");
    if (i<=xday) {document.writeln("<TD></TD>");}
    else if (i==currentdate+xday)
        {document.writeln("<TD STYLE='color:lime'>"+(i-xday)+"</TD>");}
  else {document.writeln("<TD>"+(i-xday)+"</TD>");}
  
  if (i%7==0) document.writeln("</TR>");
}

document.writeln("</TR>");
document.writeln("</TABLE>");
  }
//-->
</script><body>
  <blockquote>
     <script language="Javascript">
<!--
    displaycalender();

//-->
     </script>
  </blockquote></body>
</html>

解决方案 »

  1.   

    trydocument.writeln("<TABLE BORDER=0 STYLE='background-image:url(" + filename + ")'>");
      

  2.   

    to saucer(思归) 
    好像对了，这又是为何？
    我还以为''，两个单引是表示前后要加一个空呢！为什么是一个双引？？
    按照源里，最外面是一对“”；里面的不就都要是单引了吗？还有就是你看源码，下面还有几个地方也时有''的，那些地方要不要改，又为什么？？
      

  3.   

    把
    document.writeln("<TABLE BORDER=0 STYLE='background-image:url(''+filename+'')'>");
    改为
    document.writeln("<TABLE BORDER=0 STYLE='background-image:url(" + filename + ")'>");
      

  4.   

    document.writeln("<TABLE BORDER=0 STYLE='background-image:url(''+filename+'')'>");will display
    <TABLE BORDER=0 STYLE='background-image:url(''+filename+'')'>
    document.writeln("<TABLE BORDER=0 STYLE='background-image:url(" + filename + ")'>");will display<TABLE BORDER=0 STYLE='background-image:url(su1.jpg)'>