JSFiddle - React, Tailwind, and code Playground

HTML

<div id="display"></div>
<button type="button">Test Connection</button>

JavaScript

var online = false;
var display = $('#display');
var test = $('button').on('click', isOnline());
function isOnline(){
    $.ajax({
        async:false,
        url: "//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js",
        success:function(){
            online = true;
        },
        error:function(e){
            console.log(e);
            online=false;
        }
        
    }); 
    display.text(online);    
}

isOnline();