JSFiddle - React, Tailwind, and code Playground

HTML

<select id="ddlViewBy">
  <option value="value1">Text one</option>
  <option value="value2">Text two</option>
  <option value="value3">Text three</option>
  <option value="valueN">Text N</option>
</select>
<button id="get-value">
Get Value
</button>
<p>
Selected Value: <span id="result"></span>
</p>

JavaScript

document.querySelector('#get-value').addEventListener('click', ()=> {
  var elmValue = document.querySelector('#ddlViewBy').value;
  document.querySelector('#result').innerHTML = elmValue;
})