JSFiddle - React, Tailwind, and code Playground

HTML

<a href="" class="unique-lightbox-docid(12345-12345-12345-12345)">Download File</a>
<div id="54321">Hello...</div>
<div id="12345-12345-12345-12345">Hello...</div>
<div id="23456">Hello...</div>
<div id="12345">Hello...</div>
<div id="98765">Hello...</div>

JavaScript

var partialClassName = 'unique-lightbox-docid';

$('[class*="' + partialClassName + '"]').click(function(e){
    var fullClass = $(this).attr('class');
    var firstMatchStr = fullClass.substring(fullClass.indexOf(partialClassName), fullClass.length);
    var elementId = firstMatchStr.match(/\(.*\)/)[0].slice(1, -1);  
    alert(elementId);
    e.preventDefault();
});