JSFiddle - React, Tailwind, and code Playground

JavaScript

var keywords = [ 'An Example', 'Test'];

var str = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr\n"+
    "Test: Lorem ipsum dolor sit amet, consetetur sadipscing elitr\n"+
    "This is An Example Lorem ipsum dolor sit amet, consetetur sadipscing elitr\n"+
    "An Example Lorem ipsum dolor sit amet, consetetur sadipscing elitr";

var result = ('<p>' + str + '</p>').replace(/\r?\n/g, '</p>\r\n<p>').replace(new RegExp('^<p>(' + keywords.map(function(x){return x.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&');}).join('|') + ')(?:\\:)?\\s*', 'mgi'), '<p>$1</p>\r\n<p>');

document.body.innerHTML = result;