JSFiddle - React, Tailwind, and code Playground

HTML

<input class="searchInput" type="text">
<p id="text">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Illum adipisci a quia quas reiciendis. Consectetur excepturi iusto, corporis sapiente cupiditate quae sequi nobis voluptatibus ullam cum suscipit quibusdam quo maiores.</p>
<script>
    var searchInput = document.querySelector('.searchInput')
    var text = document.querySelector('#text')
    function displayMatches(e) {
        var regex = new RegExp(e.target.value, 'gi')
        var response = text.innerText.replace(regex, function(str) {
            return "<span style='background-color: yellow;'>" + str + "</span>"
        })
        text.innerHTML = response
    }
    searchInput.addEventListener('change', displayMatches)
    searchInput.addEventListener('keyup', displayMatches)
</script>