checkboxList判断是否被选中

 
          页面：

       checkboxlist标签 course

       cs：

             var num=0

                 for (var i = 0; i < document.aspnetForm.elements.length; i++) {

                     var e = document.aspnetForm.elements[i];

                     if ((e.type == 'checkbox') && e.name.indexOf('course') >= 0 && (e.checked == true))

                     {

                         num=1;

                     }

                 }

                 if (num>0) {

                     return true;

                 } else {

                     alert("主讲课程不能为空");

                     return false;

                 }