JSFiddle - React, Tailwind, and code Playground

HTML

<div>Este texto tem as palavras: teste, teste1 e oteste2, e eu quero filtrar as palavras teste, oteste1 e teste2</div>

JavaScript

var arr = ['teste', 'teste1', 'oteste2'];
var f = document.querySelector('div').textContent;

arr.forEach(function(el, index, arr) {
    var regexp = new RegExp("\\b(" + el + ")\\b", "g");
    console.log(regexp);
    f = f.replace(regexp, el.substr(0,1) + el.substring(1).replace(/./g, "*"));
});

document.querySelector('div').textContent = f;