JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<label for="num">num</label>
<input id="num" type="text" name="num" maxlength="14" />

CSS

input {
  width: 200px;
  padding: 5px;
}

JavaScript

document.getElementById('num').addEventListener('input', function (e) {
  e.target.value = e.target.value.replace(/[^\d]/g, '').replace(/(.{4})/g, '$1 ').trim();
});