JSFiddle - React, Tailwind, and code Playground

HTML

<form action="index.php" method="POST">
<p>Product:</p>
<select id = "myPRODUVTS">
<option> </option>
<option value = "Apple">Apple</option>
<option value = "Orange">Orange</option>
<option value = "Mango">Mango</option>
</select>
<p>Price:</p><input type="text" id="Price" name="Price" readonly />
</form>

JavaScript

$('#myPRODUVTS').on('change', function() {
 fruit = $(this).val();
    if (fruit == 'Apple') {
        $('#Price').val('£0.45');
    }
    if (fruit == 'Orange') {
        $('#Price').val('£0.50');
    }
    if (fruit == 'Mango') {
        $('#Price').val('£0.65');
    }
});