JSFiddle - React, Tailwind, and code Playground

HTML

<textarea name="" id="" cols="30" rows="10">jhkjh kjhkj hkj #jhfgdgfd dfgd @fg</textarea>

JavaScript

var textarea = document.querySelector('textarea');
textarea.addEventListener('keyup', function () {
    var text = this.value;
    var matches = text.match(/([#@][^\s]+)/g);
    if (matches) matches.forEach(function (match) {
        var tag = match.slice(0, 1);
        var texto = match.slice(1);
        console.log(tag, texto);
    });
});