JavaScript检查多个下拉列表，条件返回false无效

Question

I have multiple dropdowns created, and am checking to see if any of the class dropdown is selected. Then, it should alert and it is doing that, but the problem is the other function in the if condition as also triggering though there is a return false condition

The if condition should only trigger if the all the class dropdown are selected

JS Fiddle demo

 function addcourse() { // The .each() method is unnecessary here: $(".DD_Sub").each(function() { if ($("option:selected", this).val() == " Select Subject "); { alert(""); return false; } }); if ($("#BodyHolder_DDClass option:selected").text() == " Select Class ") { alert("Select class"); } } 

 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select name="ctl00$BodyHolder$DD_Sub1" class="DD_Sub" style="height:27px;width:150px;"> <option value="Select Subject">Select Subject</option> <option value="Holiday">Holiday</option> <option value="Lunch">Lunch</option> <option value="ECO-20">ECO-20</option> <option value="ECO-21">ECO-21</option> <option value="ECO-22">ECO-22</option> <option value="ENG-20">ENG-20</option> </select> <select name="ctl00$BodyHolder$DD_Sub1" class="DD_Sub" style="height:27px;width:150px;"> <option value="Select Subject">Select Subject</option> <option value="Holiday">Holiday</option> <option value="Lunch">Lunch</option> <option value="ECO-20">ECO-20</option> <option value="ECO-21">ECO-21</option> <option value="ECO-22">ECO-22</option> <option value="ENG-20">ENG-20</option> </select> <select name="ctl00$BodyHolder$DD_Sub1" class="DD_Sub" style="height:27px;width:150px;"> <option value="Select Subject">Select Subject</option> <option value="Holiday">Holiday</option> <option value="Lunch">Lunch</option> <option value="ECO-20">ECO-20</option> <option value="ECO-21">ECO-21</option> <option value="ECO-22">ECO-22</option> <option value="ENG-20">ENG-20</option> </select> <select name="ctl00$BodyHolder$DD_Sub1" class="DD_Sub" style="height:27px;width:150px;"> <option value="Select Subject">Select Subject</option> <option value="Holiday">Holiday</option> <option value="Lunch">Lunch</option> <option value="ECO-20">ECO-20</option> </select> <select name="ctl00$BodyHolder$DDClass" onchange="javascript:setTimeout('__doPostBack(\\'ctl00$BodyHolder$DDClass\\',\\'\\')', 0)" id="BodyHolder_DDClass" style="height:27px;width:150px;float:left;"> <option value="Select Class">Select Class</option> <option value="I BA HEG">I BA HEG</option> <option value="I BA HEK">I BA HEK</option> <option value="I BA HEP">I BA HEP</option> </select> <input type="submit" name="ctl00$BodyHolder$Add_New_period_button" value="Add Period" onclick="return addcourse();" id="BodyHolder_Add_New_period_button"> 

Answer 1

Try:

if($("option:selected").hasClass( "Select" )){
    alert("Not valid");
    return false;
}