FB.Event.subscribe & FB.Event.unsubscribe
用來listen相關facebook事件，當特定事件出現時就執行callback functionFB.Event.subscribe(event, callback function)讓我們來看一段程式碼：
FB.Event.subscribe('auth.sessionChange', function(response) {
if (response.session) {
alert(response.authResponse.accessToken);
//使用者登入，資料寫入cookies裡
} else {
alert("Ohoh");
//使用者登出，cookies被清掉
}
});
除了範例中所提到的，我們還能訂閱以下的事件：
- auth.login - fired when the auth status changes to connected
- auth.logout - fired when your app notices that there is no longer a valid user
- auth.authResponseChange - fired when the authResponse changes
- auth.statusChange - fired when the status changes (see FB.getLoginStatus for additional information on what this means)
而傳給callback function的參數"response"長得像這樣：
{
status: "", /* Current status of the session */
authResponse: { /* Information about the current session */
userID: "" /* String representing the current user's ID */
signedRequest: "", /* String with the current signedRequest */
expiresIn: "", /* UNIX time when the session expires */
accessToken: "", /* Access token of the user */
}
}
而至於unsubscribe的部分則是subscribe的相反，就是取消listen特定事件，可以自己試試看。
FB.login
顧名思義，就是以facebook登入所在網站。前提是你必須先用FB.init設定了SDK環境、設定appId。FB.login(callback function, permissions scope)來，讓我們再
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: 'user_about_me,email,user_likes'});
這邊要注意的是第二個參數是一個object，只有一組key:value，key一定是"scope"，value是一連串以permission組成的String，中間以逗號分開。scope中所指定的就是要從使用者那拿到的授權，要看詳細清單可以看facebook的官方文件。
FB.getLoginStatus
基本上在一個facebook應用中我們需要判斷使用者是以下三個狀態中的哪一種：- 使用者登入了facebook也授權給你的應用程式 (connected)
- 使用者登入了facebook但還沒授權給你的應用程式 (not_authorized)
- 根本沒登入 (unknown)
這時我們就可以使用FB.getLoginStatus來搞清楚使用者的狀態
FB.getLoginStatus(callback function, force)force是一個boolean，會強制reload使用者的登入狀態(預設為false)
我們再來偷一段程式碼來搞清楚他的用法：
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.
}
});
response object:
{
status: 'connected',
authResponse: {
accessToken: '...',
expiresIn:'...',
signedRequest:'...',
userID:'...'
}
}
