js对象转json字符串

function obj2str(o){
		    var r = [];
		    if(typeof o =="string") return "\""+o.replace(/([\'\"\\])/g,"\\$1").replace(/(\n)/g,"\\n").replace(/(\r)/g,"\\r").replace(/(\t)/g,"\\t")+"\"";
		    if(typeof o =="undefined") return "";
		    if(typeof o == "object"){
		        if(o===null) return "null";
		        else if(!o.sort){
		            for(var i in o)
		                r.push(i+":"+obj2str(o[i]))
		            r="{"+r.join()+"}"
		        }else{
		            for(var i =0;i<o.length;i++)
		                r.push(obj2str(o[i]))
		            r="["+r.join()+"]"
		        }
		        return r;
		    }
		    return o.toString();
		}