通过前端sdk 做facebook登录

1.首先通过前端FB.init初始化，其中很重要的参数就是appId,该参数需要在facebook developer平台申请，创建应用，添加相应的ip 地址或者域名。

2.引入facebook 提供的js,获取facebook用户信息

3.将用户信息传给后台程序，将用户信息存入数据库。

 <script>
     logInWithFacebook= function() {
         FB.login(function(response) {
             if (response.authResponse) {
                 var accessToken =response.authResponse.accessToken;
                 FB.api('/me?fields=name,email,first_name,last_name', function(response) {
                     userEmail=response.email;
                     if(response.email!=null){
                         $.ajax({
                             url:"<?=Yii::$app->urlManager->createUrl(['account/third-part-login']); ?>",
                             data:{
                                 userName:response.name,
                                 firstName:response.first_name,
                                 lastName:response.last_name,
                                 email:response.email,
                                 access_token:accessToken,
                                 third_part_type:'facebook',
                                 openid:response.id,
                                 image:''
                             },
                             dataType:"json",
                             type:"post",
                             success:function(data){
                                 if(data.code=200){
                                     window.location =data.url;
                                 }
                             }
                         });
                     }else{
                         alert("It fails to login within third part.");
                     }

                 });

                 //alert('You are logged in &amp; cookie set!');
                 // Now you can redirect the user or do an AJAX request to
                 // a PHP script that grabs the signed request from the cookie.
             } else {
                 alert('User cancelled login or did not fully authorize.');
             }
         },{scope: 'email'});
         return false;
     };
     window.fbAsyncInit = function() {
         FB.init({
             appId: "<?php echo Yii::$app->params['fb_app_id'];?>",
             cookie: true, // This is important, it's not enabled by default
             version: 'v2.9'
         });
     };

     (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>