JSFiddle - React, Tailwind, and code Playground

HTML

<form action="#">
<textarea class="input" name="input" type="text" id="txt" />test</textarea>
<input type="button" value="Run" id="run"/>
</form>

JavaScript

$(document).ready(function() {
    $('#run').click(function() {
    var textarea=$('#txt'); 
    textarea.val(textarea.val().replace(/test/g,"ok"));
    });
});