how to get email id of Facebook user using javascript sdk

Question

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> 

Answer 1

// 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);   } );