一个方便AJAX开发的通用类

;       catch(e2) {
            try { xmlObj=new ActiveXObject("Microsoft.XMLHTTP"); }
            catch(e3) { xmlObj=false; }
        }
    }
    if (!xmlObj) return false;
    if(arguments[0]) this.url=arguments[0]; else this.url="";
    if(arguments) this.callback=arguments; else this.callback=function(obj){return};
    if(arguments) this.content=arguments; else this.content="";
    if(arguments) this.method=arguments; else this.method="POST";
    if(arguments) this.async=arguments; else this.async=true;
    this.send=function() {
        var purl,pcbf,pc,pm,pa;
        if(arguments[0]) purl=arguments[0]; else purl=this.url;
        if(arguments) pc=arguments; else pc=this.content;
        if(arguments) pcbf=arguments; else pcbf=this.callback;
        if(arguments) pm=arguments; else pm=this.method;
        if(arguments) pa=arguments; else pa=this.async;
        if(!pm||!purl||!pa) return false;
        xmlObj.open (pm, purl, pa);
        if(pm=="POST") xmlObj.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        xmlObj.onreadystatechange=function() {
            if(xmlObj.readyState==4) {
                if(xmlObj.status==200) {
                    pcbf(xmlObj);
                }
                else {
                    pcbf(null);
                }
            }
    &n