JSFiddle - React, Tailwind, and code Playground

HTML

<h4>Online Users</h4>
<ul>
<li onClick="window.open('http://stackoverflow.com/', '')">John</li>
<li onClick="open()">John</li>
</ul>

JavaScript

function open()
{
    var win = window.open('http://stackoverflow.com/', '');
    
    if(win){
        win.focus();
    }else{
        alert('Please allow popups for this site');
    }
}