how to get email id of Facebook user using javascript sdk

问题

I am using JavaScript API to create my app for Facebook. The problem is, it's returning
email = undefined.

I don't know why? And if I use Facebook login/logout button on my app then the alert shows correct email id of the user but I don't want to do that. What am I missing?

Here is my code:

<p><fb:login-button autologoutlink="true" perms="user_about_me,email"></fb:login-button></p>

<script>
window.fbAsyncInit = function () {
  FB.init({ appId: '250180631699888', status: true, cookie: true,
  xfbml: true
});

  FB.getLoginStatus(function (response) {
    if (response.session) {
      greet();
    }
  });
};
(function () {
  var e = document.createElement('script');
  e.type = 'text/javascript';
  e.src = document.location.protocol +
  '//connect.facebook.net/en_US/all.js';
  e.async = true;
  document.getElementById('fb-root').appendChild(e);
} ());

function greet() {
  FB.api('/me', function (response) {
  alert('Welcome, ' + response.name + "!");
  alert('Your email id is : '+ response.email);
});
}
</script>

回答1:

According to the latest info on the facebook page you should use 'scope' instead of perms. https://developers.facebook.com/docs/reference/javascript/FB.login/

If you visit

https://developers.facebook.com/tools/console/

and use the fb-api -> user-info example as a starting point, then logout and back in again, it should ask you for email perms and you can see your email being printed. It is done using response.email as you mention in your post.

回答2:

// https://developers.facebook.com/docs/javascript/reference/FB.api/
// v2.4

FB.api('/me', { locale: 'en_US', fields: 'name, email' },
  function(response) {
    console.log(response.email);
  }
);

回答3:

here is example how i retrieve user name and e-mail:

<div id="fb-root"></div>
<script src="http://connect.facebook.net/en_US/all.js"></script>

<script>
  $(function() {
    FB.init({
      appId  : 'APP_ID',
      status : true, // check login status
      cookie : true, // enable cookies to allow the server to access the session
      xfbml  : true  // parse XFBML
    });

    FB.getLoginStatus(function(response) {
      if (response.status == 'connected') {
        getCurrentUserInfo(response)
      } else {
        FB.login(function(response) {
          if (response.authResponse){
            getCurrentUserInfo(response)
          } else {
            console.log('Auth cancelled.')
          }
        }, { scope: 'email' });
      }
    });

    function getCurrentUserInfo() {
      FB.api('/me', function(userInfo) {
        console.log(userInfo.name + ': ' + userInfo.email);
      });
    }
  });
</script>

回答4:

<button id="fb-login">Login & Permissions</button>

<script>
document.getElementById('fb-login').onclick = function() {
  var cb = function(response) {
    Log.info('FB.login callback', response);
    if (response.status === 'connected') {
      Log.info('User logged in');
    } else {
      Log.info('User is logged out');
    }
  };
  FB.login(cb, { scope: 'email' });
};
</script>

Use this to for extra permission

for more details visit : https://www.fbrell.com/examples/

回答5:

In this code i have get user data form facebook and store into my database using ajax

 FB.login(function(response) {
          if (response.authResponse) {
         FB.api('/me?fields=email,name,first_name,last_name', function(response) 
         {
             FB.api(
             "/"+response.id+"/picture?height=100",
                                    function (responses) {
                                        //console.log(responses.data.url)
                                                    response['profile_pic']=responses.data.url;
                                        $.ajax({
                                                   type:"POST",
                                                   url:'<?php echo base_url(); ?>'+'home/facebook_get_signup',
                                                   data:response,
                                                   success:function(res)
                                                   {
                                                       if(res=='success')
                                                       {

                                                           window.location='<?php echo base_url(); ?>';
                                                       }
                                                       if(res=='exists')
                                                       {
                                                           window.location='<?php echo base_url(); ?>';  
                                                       }
                                                   }
                                               });

                                    }
                                )
         });
        } else {
         console.log('User cancelled login or did not fully authorize.');
        } 
      // handle the response
        }, {scope: 'email,user_likes'});

回答6:

There are a couple of things wrong with your solution. First of all you are using the old authentication scheme. You should use the new one described here : https://developers.facebook.com/docs/reference/javascript/

You need to add the oauth:true to your init function, and make sure that your getLoginStatus looks for the new type of response.

When that is said you need to make sure you have the right permissions to see the users e-mail. You can see the required permissions here: http://developers.facebook.com/docs/reference/api/user/

You get those by using the FB.login function as described by TommyBs in another answer.

Once you have those options you can use the FB.api function to get the e-mail.

来源：https://stackoverflow.com/questions/7820485/how-to-get-email-id-of-facebook-user-using-javascript-sdk