JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="my-textarea"></textarea>

JavaScript

document.querySelector('#my-textarea').addEventListener('input', (event) => {
	if (event.target.value.includes('http') || event.target.value.includes('https') || event.target.value.includes('www')) {
  	console.log('invalid');
  } else {
  	console.log('valid');
  }
});