JSFiddle - React, Tailwind, and code Playground

HTML

<h2>註冊</h2>
<lable for="account"></lable>
<input id="account" type="text">
<lable for="pwd"></lable>
<input id="pwd" type="password">
<button type="submit" id="registerSmtBtn">Signup</button>

<h2>登入</h2>
<lable for="accountL"></lable>
<input id="accountL" type="text">
<lable for="pwdL"></lable>
<input id="pwdL" type="password">
<button type="submit" id="loginSmtBtn">Login</button>

<h2>登出</h2>
<button id="signoutSmtBtn">Signout</button>

<h2>電子郵件驗證</h2>
<button id="verifyBtn">Verify</button>

<h2>更改密碼</h2>
<label for="chgPwd">Email</label>
<input id="chgPwd" type="text">
<button id="chgPwdBtn">ChangePwd</button>

<h2>Facebook登入</h2>
<button id="fbLoginBtn">FB Login</button>

<script src="https://www.gstatic.com/firebasejs/3.5.2/firebase.js"></script>

JavaScript

// Initialize Firebase
  var config = {
    apiKey: "AIzaSyAi2nICnl0EDIcYF-6VCTfNRixOdPzAQV4",
    authDomain: "iiefsstest.firebaseapp.com",
    databaseURL: "https://iiefsstest.firebaseio.com",
    projectId: "iiefsstest",
    storageBucket: "iiefsstest.appspot.com",
    messagingSenderId: "530094645810"
  };
  firebase.initializeApp(config);

//Email/Pwd註冊
var account = document.getElementById("account");
var pwd = document.getElementById("pwd");
var registerSmtBtn = document.getElementById("registerSmtBtn");
registerSmtBtn.addEventListener("click", function(){
		console.log(account.value);
    firebase.auth().createUserWithEmailAndPassword(account.value, pwd.value).catch(function(error) {
    // Handle Errors here.
    var errorCode = error.code;
    var errorMsg = error.message;
    console.log(errorMsg);
  });
},false);

//登入
var accountL = document.getElementById("accountL");
var pwdL = document.getElementById("pwdL");
var loginSmtBtn = document.getElementById("loginSmtBtn");
loginSmtBtn.addEventListener("click",function(){
	console.log(accountL.value);
	firebase.auth().signInWithEmailAndPassword(accountL.value, pwdL.value).catch(function(error) {
  	// Handle Errors here.
  	var errorCode = error.code;
  	var errorMessage = error.message;
  	console.log(errorMessage);
  })
},false);

//登出
var signoutSmtBtn = document.getElementById("signoutSmtBtn");
signoutSmtBtn.addEventListener("click",function(){
	firebase.auth().signOut().then(function() {
		console.log("User sign out!");
	}, function(error) {
  	console.log("User sign out error!");
	})
},false);

//Email驗證
var verifyBtn = document.getElementById("verifyBtn");
verifyBtn.addEventListener("click",function(){
  user.sendEmailVerification().then(function() {
    console.log("驗證信寄出");
  }, function(error) {
   	console.error("驗證信錯誤");
  });
},false);

//更改密碼
var chgPwd = document.getElementById("chgPwd");
var chgPwdBtn =...