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();
}