1.把字符串转化为json对象

var str='{"email":"账号不能为空","password":"密码不能为空"}'
var alert(json.email) =jQuery.parseJSON(str);

2.访问json对象

alert(json.email);

?

3.遍历json对象

$.each(json, function(key, val){
     alert("name:"+key+" value:"+val);
});