JSFiddle - React, Tailwind, and code Playground

by pavlukd

HTML

<input type="tel" placeholder="+48 111-111-111" id="phone" name="phone" data-field="item" minlength="9" required>
<input id="but1" value="ZamĂłwic" type="submit">

JavaScript

phone.addEventListener('keyup', function(evt){
  let length = this.value.length
  if (length < 9) document.getElementById('but1').disabled = true;
  else if (length == 9) document.getElementById('but1').disabled = false;
  else if (length > 9) document.getElementById('but1').disabled = true;
})