JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://www.gstatic.com/firebasejs/3.6.4/firebase.js"></script>

JavaScript

// Initialize Firebase
  var config = {
    apiKey: "AIzaSyBs7XEck3J0iA4fuCJvEdHr8PyISa27Dqc",
    authDomain: "usage-test-ce01e.firebaseapp.com",
    databaseURL: "https://usage-test-ce01e.firebaseio.com",
    storageBucket: "usage-test-ce01e.appspot.com",
    messagingSenderId: "1002430298292"
  };
  firebase.initializeApp(config);
  
 firebase.database().ref("test").once("value", function(snapshot) {
   console.log(snapshot.val());
 });