JSFiddle - React, Tailwind, and code Playground
HTML
<p>
ID:
<input type="text" id="id" name="id" value="21" />
</p>
<p>
Color:
<select id="color" name="color">
<option value="black" selected="selected">Black</option>
<option value="white">White</option>
</select>
</p>
JavaScript
$('#color').on('change',function(e){
var codes = {
'black': 21,
'white': 22
};
$('#id').val(codes[$(this).val()]);
});