二楼少了个括号
var json = eval("("+str+")");
你这个是个字符串。JSON.parse一下就行了
var str = {"code":0,"data":[{"uid":"689791","username":"vaghyuzhihao","orgid":"627","status":"1","subname":"yuzhihao","roleids":"1","orgcode":"600251","name":"yuzhihao","mapid":"0","passwd":"","siteid":"0","createorgcode":"600251","alarmview":"0"}]};
var json = eval(str);
console.log(json.data[0].uid);
一般返回的都是字符串,需要对其对象化
你前台是用什么接收的?