javascript - 未定义未处理的 Promise Rejection

Question

在我的 React Native 应用程序中，我有一个自定义登录 Facebook 按钮:

<Button onPress={() => this.handleFacebookLogin()}>
  <Text>Login with Face</Text>
</Button>

还有handleFacebookLogin函数:

 handleFacebookLogin () {
     LoginManager.logInWithReadPermissions(['public_profile', 'email', 'user_friends']).then(
       function (result) {
         if (result.isCancelled) {
           console.log('Login cancelled')
         } else {
           console.log('Login success with permissions: ' + result.grantedPermissions.toString())
           AccessToken.getCurrentAccessToken().then(
             (data) => {
               signInFacebookLoginInFirebase(data.accessToken)
               //this.signInFacebookLoginInFirebase(data.accessToken)
             }
           )
         }
       },
       function (error) {
         console.log('Login fail with error: ' + error)
         alert('Error at login, no network ?')
       }
     )
 }

但我收到此错误:

Possible Unhandled Promise Rejection (id: 20): ReferenceError: signInFacebookLoginInFirebase is not defined TypeError: _this2.signInFacebookLoginInFirebase is not a function

类型错误:_this2.signInFacebookLoginInFirebase 不是函数

和signInFacebookLoginInFirebase方法:

   signInFacebookLoginInFirebase(facebookToken){
     const credential = Fb.firebase.auth.FacebookAuthProvider.credential(facebookToken);
     Fb.firebase
       .auth()
       .signInWithCredential(credential)
       .then(() => alert('Account accepted'))
       .catch((error) => alert('Account disabled'));
   }

Answer 1

如果您的 .then 回调不使用箭头符号来 logInWithReadPermissions，this 将不会成为您的 signInFacebookLoginInFirebase< 的上下文 函数

您在AccessToken.getCurrentAccessToken().then中使用箭头表示法，这样很好，现在您只需更改

LoginManager.logInWithReadPermissions(['public_profile', 'email', 'user_friends']).then(
    function (result) {

至

LoginManager.logInWithReadPermissions(['public_profile', 'email', 'user_friends']).then(
    (result) => {

然后使用注释掉的

this.signInFacebookLoginInFirebase(data.accessToken);

为了正确处理所有潜在的拒绝，我建议

handleFacebookLogin () {
    LoginManager.logInWithReadPermissions(['public_profile', 'email', 'user_friends'])
    .then(result => {
        if (result.isCancelled) {
            console.log('Login cancelled');
        } else {
            console.log('Login success with permissions: ' + result.grantedPermissions.toString())
            return AccessToken.getCurrentAccessToken()
            .then(data => this.signInFacebookLoginInFirebase(data.accessToken));
        }
    // .catch chained from .then to handle all rejections
    }).catch(error => {
        console.log('Login fail with error: ' + error);
        alert('Error at login, no network ?');
    })
}