Bootstrap Datepicker deletes input fields default value

I’m using boostrap datepicker (I think), it works fine and dandy. However,

-jquery loads a date into the input field when the page loads (not related to datepicker)
-user clicks on the input field, datepicker modal appears
-problem: if the modal shows and the user does not click a date (clicks something else), the original date in the input is deleted.

$('#period_end').datepicker({ format: 'yyyy-mm-dd', autoclose : true, todayHighlight : true });
<input type="text" class="form-control required" placeholder="yyyy-mm-dd" id="period_end" name="period_end" autocomplete="off">

I would be extremely grateful for some help, its not easy to have a beginner question answered.

Jolly Boy.