JSFiddle - React, Tailwind, and code Playground
by Oleg Lazarev
HTML
<style>
:invalid { background: red; }
:valid { background: green; }
</style>
<input pattern="a.b" value="aXXb"><!-- получаем красный background -->
<input pattern="a.b" value="a𝌆b"><!-- получаем зеленый background -->