JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdn.firebase.com/js/client/1.0.17/firebase.js"></script>

JavaScript

var MyVariable = '';
$( document ).ready(function() {
var ref = new Firebase('https://helloworldtest.firebaseIO.com/');

MyVariable = ref.on('value', function (snapshot) {
    var Variable = snapshot.child("text").val();
    return Variable;
});


alert(MyVariable);
});