Facebook Login Sdk

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Facebook Login Sdk
Facebook API – Login with the JavaScript SDK
I´ve seen a lot of weird coding happening around Login with the Facebook JavaScript SDK, so here is one good solution with explanation.
HTML (just a login button and a div for the response)

Of course there is room for improvement (there always is), but i am just trying to explain when (and how) you should use FB.login and FB.getLoginStatus. For example, you should hide the login button with CSS, right now it shows up for a short time and disappears if the user is authorized already – because it takes some time until the callback function of FB.getLoginStatus gets called. You could also use the Social Plugin for the Login Button, but i guess you want to use your own design so that´s not an option in most cases.

FB.login: FB.login opens the authorization window where users can authorize your App. It must get called directly on user interaction (mouse click), you can´t call it right after FB.init and you can´t call it in the asynchronous callback function of FB.getLoginStatus either. Make sure you understand what asynchronous means, it´s very important to know for a web developer. If you don´t call it on user interaction, it may get blocked by popup blockers. The benefit of using FB.login for authorization is that you don´t need to redirect the user to a login screen – the PHP SDK does not offer that kind of usability.

Related Posts:
FB.getLoginStatus: This function should get used on page load, right after FB.init. The major advantage of using this instead of a server side login process (with the PHP SDK, for example) is that it will refresh the User Token without page refresh. That is another benefit of using the JavaScript SDK, and it´s a pretty important one.

FB.api: This is actually not about the login process anymore, it´s just a basic API call to get the basic user data in the example. FB.api can only be used after FB.init. Should be obvious though, you can´t use the API before initializing the SDK.

return_scopes: Asking for permissions in the authorization process is not a sure thing. The user can just deselect the email permission in the authorization popup, for example. It´s quite easy to check for the authorized permissions by setting return_scopes in FB.login, as you can see in the code. If you add that parameter, you will get a list of all granted permissions in the grantedScopes field of response.authResponse.

That´s it, if you got any improvement tips or find any errors, feel free to comment – here are some links to the Facebook docs, if you need more information:
Facebook Login Sdk Facebook Login Sdk Reviewed by Efukikata Efet on 14:59 Rating: 5

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