how to convert string to integer in below code

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C#

jQuery

I have the Code As follows :

qcAllocationDetails.BatchId = $("#batchIDSelect option:selected").map(function () {
       return $(this).val();
}).get().join(',');
   console.log(qcAllocationDetails.BatchId);

Ihave the controls as follows:

<select id="batchIDSelect" name="batchIDSelect" class="combo100" multiple="multiple">
                        </select>

I can select number of values from BatchId .My BatchId is Integer.Values are 1,2,3...and so on
its gives me error could not convert string to integer.Is there anyway to sort this problem.
In my above code ,where should i make the changes.Please guide me.I want to pass a string instead of integer .How is it possible.

Thanks
Harshal.