javascript判断用户浏览器插件安装情况的代码

document.writeln("<TABLE BORDER=1><TR VALIGN=TOP>", 
"<TH ALIGN=left>i", 
"<TH ALIGN=left>名称", 
"<TH ALIGN=left>文件名", 
"<TH ALIGN=left>描述", 
"<TH ALIGN=left>类型数</TR>") 
for (i=0; i < navigator.plugins.length; i++) { 
document.writeln("<TR VALIGN=TOP><TD>",i, 
"<TD>",navigator.plugins[i].name, 
"<TD>",navigator.plugins[i].filename, 
"<TD>",navigator.plugins[i].description, 
"<TD>",navigator.plugins[i].length, 
"</TR>") 
} 
document.writeln("</TABLE>");