如何使用json将数据发送到键值结构的后端

Question

var idd ;
var subjects        =   [];
var ctr             =   0;

var teacher         =   $('#selectTeacher option:selected').text();

for(var j = 0 ; j < lstClasses.length ; j++)
{  
    var sub         =   {};
    var key         =   lstClasses[j];

    for(var i = 0 ; i < lstSubjects.length ; i++)
    {
        var id      =   lstClasses[j] + lstSubjects[i];
        var cls     =   $('#'+id).attr('class');

        if(cls.indexOf('tickimage') >= 0)   
        {   
            if(ctr  ==  0)
            {
                var val     =   [];
            }

            ctr     =   ctr +   1;
            idd     =   id.replace(lstClasses[j], "");

            val.push(idd);
            /* console.log(val); */

            sub[key]    =   val; 
        }
        /* console.log(sub); */
        subjects.push(sub);
    }
  }

我发送的数据不会以json格式正确后端。我只是想发送特定的类数据及其主题但是在发送数据时它不正常