FB.getLoginStatus 弹出窗口内的 FB.login 被阻止

我正在尝试使用 Facebook Javascript SDK 将 Facebook 登录集成到我的网站中。根据Facebook开发者文档提供的分步说明here https://developers.facebook.com/docs/javascript/quickstart/v2.2#login，这是我写的测试代码：

<script>
window.fbAsyncInit = function() {
    FB.init({
        appId      : '{$MY_APP_ID}',
        cookie     : true,  // enable cookies to allow the server to access the session
        xfbml      : true,  // parse social plugins on this page
        version    : 'v2.1', // use version 2.1
        status     : true,   // check FB login status
    });
};

function fblogin() {
    FB.getLoginStatus(function(response) {
      if (response.status === 'connected') {
        alert('Logged in.');
      }
      else {
        FB.login();
      }
    }, true);
}
</script>
<button onclick="fblogin()">login</button>
<script src="//connect.facebook.net/en_US/sdk.js"></script>

抱歉，由于网站域名的限制，我不能拿这个来摆弄。但我在自己的域上尝试过，Chrome 和 Firefox 中都会弹出 Facebook 登录窗口，但被 Safari 阻止。这有点奇怪，Facebook开发者文档提供的代码片段有什么问题吗？

正如我们在评论中已经讨论的那样，必须在用户交互时调用 FB.login，文档中的示例不正确。

这应该是一个如何正确登录的工作示例，从 Facebook 文档中的几篇文章一起复制：

<script>
    //call this on user interaction (click)
    function doLogin() {
        FB.login(function(response) {
            if (response.authResponse) {
                console.log('Welcome!  Fetching your information.... ');
                FB.api('/me', function(response) {
                    console.log('Good to see you, ' + response.name + '.');
                });
            } else {
                console.log('User cancelled login or did not fully authorize.');
            }
        }, {scope: 'email,user_friends'});
    }

    window.fbAsyncInit = function() {
        FB.init({
            appId      : 'your-app-id',
            xfbml      : true,
            version    : 'v2.1'
        });

        FB.getLoginStatus(function (response) {
            if (response.status === 'connected') {
                // the user is logged in and has authenticated your
                // app, and response.authResponse supplies
                // the user's ID, a valid access token, a signed
                // request, and the time the access token 
                // and signed request each expire
                var uid = response.authResponse.userID;
                var accessToken = response.authResponse.accessToken;
            } else if (response.status === 'not_authorized') {
                // the user is logged in to Facebook, 
                // but has not authenticated your app
            } else {
                // the user isn't logged in to Facebook.
            }
        });
    };

    (function(d, s, id){
        var js, fjs = d.getElementsByTagName(s)[0];
        if (d.getElementById(id)) {return;}
        js = d.createElement(s); js.id = id;
        js.src = "//connect.facebook.net/en_US/sdk.js";
        fjs.parentNode.insertBefore(js, fjs);
    }(document, 'script', 'facebook-jssdk'));
</script>
<button onclick="doLogin()">login</button>

更多解释：http://www.devils-heaven.com/facebook-javascript-sdk-login/ http://www.devils-heaven.com/facebook-javascript-sdk-login/