JSFiddle - React, Tailwind, and code Playground

HTML

<div id='permalink_section'>
  <a id="longlink" href="123456789012345678901234567890123456789012345678901234567890">123456789012345678901234567890123456789012345678901234567890</a>
</div>

<br><br>
<button onclick="javascript: truncLink();">Truncate Link</button>

JavaScript

function truncLink()
{
    var linkText = $("#longlink").text();
    if (linkText.length>20) {
        $("#longlink").text(linkText.substring(0, 20) + " ...");
        }
}