JSFiddle - React, Tailwind, and code Playground

HTML

<select id="category">
    <option value="1" data-price="10">Item 1 second</option>
    <option value="2" data-price="20">Item 2 second</option>
    <option value="3" data-price="30">Item 3 second</option>
</select>
<br>
<br>
<label>Dept. num:</label>
<input type="text" id="dept-input"></input>
<br>
<br>
<label>Price:</label>
<input type="text" id="price-input"></input>

JavaScript

$("#category").change(function () {
    var dept_number = $(this).val();
    var price = $(this).find(':selected').data('price');
    $('#dept-input').val(dept_number);
    $('#price-input').val(price);
});