JSFiddle - React, Tailwind, and code Playground

JavaScript

(function () {
    var originalFetch = fetch;
        fetch = function() {
        return originalFetch.apply(this, arguments).then(function(data) {
            someFunctionToDoSomething();
            return data;
        });
    };
    function someFunctionToDoSomething() {
        log("someFunctionToDoSomething called");
    }
})();
log("Fetching...");
fetch("/echo/json/").then(function(result) {
    log("Got result");
});
function log(msg) {
	var p = document.createElement("pre");
  p.appendChild(
  	document.createTextNode(msg)
  );
  document.body.appendChild(p);
}