JSFiddle - React, Tailwind, and code Playground
by Bill Ostaski
HTML
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<td width="200px">
<select name="1-duration" id="duration-1">
<option value="">Select</option>
<option value=".5">.5 hr</option>
<option value="1">1 hr</option>
<option value="1.5">1.5 hrs</option>
<option value="2">2 hrs</option>
<option value="2.5">2.5 hrs</option>
<option value="3">3 hrs</option>
<option value="3.5">3.5 hrs</option>
<option value="4">4 hrs</option>
</select>
</td>
<td width="200px"><input type="text" name="1-promDate" value="" id="promDate-1">
</td>
JavaScript
var employeeID = 1;
var selectID = "#duration-" + employeeID;
var textID = "#promDate-" + employeeID;
var displayDate = "04/09/2017";
$(selectID).change(function(){
$(textID).val(displayDate);
});