Firebase core.js:4197错误类型错误：无法读取属性'；TwitterAuthProvider'；未定义的

我越来越 core.js:4197错误类型错误：无法读取未定义的属性“TwitterAuthProvider”

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运行应用程序时出错

错误表明

firebase.auth

未定义。请编辑问题以显示如何导入Firebase Auth SDK。您可能需要返回并按照说明再次开始使用SDK；从“firebase/app”导入*作为firebase```这就是我添加@dougstevenson的方式。您能帮助我为firebase提供程序设置身份验证吗

   var provider = new firebase.auth.TwitterAuthProvider();
  firebase.auth().signInWithPopup(provider).then(function(result) {
    // This gives you a the Twitter OAuth 1.0 Access Token and Secret.
    // You can use these server side with your app's credentials to access the Twitter API.
    // var token = result.credential.accessToken;
    // var secret = result.credential.secret;
    // The signed-in user info.
    var user = result.user;
    console.log(user);
    // ...
  }).catch(function(error) {
    // Handle Errors here.
    var errorCode = error.code;
    var errorMessage = error.message;
    // The email of the user's account used.
    var email = error.email;
    // The firebase.auth.AuthCredential type that was used.
    var credential = error.credential;
    // ...
  });