JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://aldonline.github.io/syncify/build/syncify-1.1.0.min.js"></script>

JavaScript

var callbackTest = function(k, cb) {
    setTimeout(function() {
        console.log("callbackTest => cb(\"" + k + "\")");
        cb(k);
    }, 2000);
};

callbackTest = syncify(callbackTest);

function getCallbackText() {
    console.log("Evaluating getCallbackText()");
    return callbackTest("Alice") + " " + callbackTest("Bob");
}

getCallbackText = syncify.revert(getCallbackText);

console.log("Pre-callback");

getCallbackText(function (err, v) {
    console.log("Callback returned: " + v);
});

console.log("Post-callback");