js中activeXString是什么

Question

在代码：

function createXHR(){
  if(typeof XMLHttpRequest !="undefined"){
  return new XMLHttpRequest(); 
}else if(typeof ActiveXObject !="undefined"){
   if(typeof arguments.callee.activeXString !="string"){
   var versions = ["MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.3.0","MSXML2.XMLHttp"];
   var i,len;
   for (i=0,len=versions.length;i<len;i++){
   try{
   new ActiveXObject(versions[i]);
    arguments.callee.activeXString = versions[i];
    break;
}catch(ex){}
}
}
return new ActiveXObject(arguments.callee.activeXString);
}else{
throw new Error("No XHR object available");
}
}

在上述代码中activeXString是什么呢

Answer 1

function Foo() {

// do something;
// arguments.callee.activeXString === 'foo';

};
Foo.activeXString = 'foo';