JSFiddle - React, Tailwind, and code Playground
by Joe
HTML
<select id="s_id">
<option value="option1">option1</option>
<option value="option2">option2</option>
<option value="option3">option3</option>
<option value="option4">option4</option>
</select>
number: <input type="text" name="number">
JavaScript
$("#s_id").change(function () {
var isReadonly = ['option3', 'option4'].indexOf(this.value) > -1;
$("input[name='number']").prop('readonly', isReadonly);
});