SharePoint New and Edit Form Javascript Date Time Field

I have a custom list that contains a date time field. The client requested we trim the time portion of the field to only show two available appointment times of 8:30 am and 1:30 pm. In order to do this I added the following javascript code to the New and Edit forms of the list. The problem I am having is when the users open the edit form it does not maintain the previously selected time value. It shows the first available value of 8:30 AM, so if the users open the edit form and change some other field than the time field they inadvertently change the originally selected time field to 8:30 am even if the originally selected time was 1:30PM. How can I get the code to default to the originally selected time value from the New form within Edit form?

$(document).ready(function () { var str=['8 AM','1 PM']; $("select[id$='_DateTimeField_DateTimeFieldDateHours']").each(function(i){ $(this).html(""); for(var i=0;str[i]!=null;i++){ $(this).append(''+str[i]+''); } }); }); $(document).ready(function () { var str=['30']; $("select[id$='_DateTimeField_DateTimeFieldDateMinutes']").each(function(i){ $(this).html(""); for(var i=0;str[i]!=null;i++){ $(this).append(''+str[i]+''); } }); });