In this tutorial,I have covered how to use Facebook Javascript SDK.
Using this SDK, you can get the full functionality of Facebook OAuth at client-side.
i.e., Getting User Information/Posting to Wall/Reading Messages can be done with pure JavaScript, It doesn’t require any server-side programming.
List of Core APIs in Facebook Javascript SDK
FB.init – Initialize the SDK with your APP ID
FB.api – For making API calls to Graph API
FB.ui – For triggering Facebook Dialogs like OAuth Dialog, Feed Dialog, Friends Dialog, Request Dialog, Send Dialog, Pay Dialog, Add Page Tab Dialog
FB.login – Login to Facebook using OAuth Dialog
FB.logout – Logout the user from Facebook
FB.getLoginStatus – For checking whether user is logged in and authenticated App
FB.getAuthResponse – Similar to FB.getLoginStatus, but it is synchronous and returns authResponse Object.
FB.Event.subscribe – Subscribe for events (auth.login, auth.authResponseChange, auth.statusChange) and get callbacks to your function when event is fired.
FB.Event.unsubscribe – Unsubscribe the specified events
Follow the below steps to make your first JavaScript App:
1) You need a Facebook App ID to use Facebook Javascript SDK,
Check “Creating Facebook App” section in http://hayageek.com/facebook-dialog-oauth/
2). Add a Channel file in your website. Channel file is optional but it improves the Facebook Javascript SDK performance by addressing cross-domain issues in certain browsers.
content of channel file is
<script src="//connect.facebook.net/en_US/all.js"></script>
3) Facebook SDK initialization. Add the below code to your HTML file.
<div id="fb-root"></div>
<script>
window.fbAsyncInit = function() {
FB.init({
appId : 'YOUR_APP_ID', // App ID
channelUrl : 'YOUR_WEBSITE_CHANNEL_URL',
status : true, // check login status
cookie : true, // enable cookies to allow the server to access the session
xfbml : true // parse XFBML
});
};
(function(d){
var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
if (d.getElementById(id)) {return;}
js = d.createElement('script'); js.id = id; js.async = true;
js.src = "//connect.facebook.net/en_US/all.js";
ref.parentNode.insertBefore(js, ref);
}(document));
</script>
4) Write a Method for Login
Use Fb.login() method for asking user authorization.If you want extra information from user, you need to provide the necessary scope list.
for email : – {scope: ’email’}
for Friends List – {scope: ‘read_friendlists’}
For Photos,Videos – {scope: ‘user_photos,user_videos’}
function Login()
{
FB.login(function(response) {
if (response.authResponse)
{
getUserInfo(); // Get User Information.
} else
{
console.log('Authorization failed.');
}
},{scope: 'email'});
}
5) Get User Information by making API call to Graph API
function getUserInfo() {
FB.api('/me', function(response) {
//response.name - User Full name
//response.link - User Facebook URL
//response.username - User name
//response.id - id
//response.email - User email
});
}
6) Add callback handler for authResponseChange events. This is optional.
FB.Event.subscribe('auth.authResponseChange', function(response)
{
if (response.status === 'connected')
{
//SUCCESS
}
else if (response.status === 'not_authorized')
{
//FAILED
} else
{
//UNKNOWN ERROR. Logged Out
}
});
6) Write a Method for Logout
function Logout()
{
FB.logout(function(){document.location.reload();});
}
Working Facebook Javascript SDK Example
<html>
<body>
<div id="fb-root"></div>
<script>
window.fbAsyncInit = function() {
FB.init({
appId : '113455642165175', // Set YOUR APP ID
channelUrl : 'http://hayageek.com/examples/oauth/facebook/oauth-javascript/channel.html', // Channel File
status : true, // check login status
cookie : true, // enable cookies to allow the server to access the session
xfbml : true // parse XFBML
});
FB.Event.subscribe('auth.authResponseChange', function(response)
{
if (response.status === 'connected')
{
document.getElementById("message").innerHTML += "<br>Connected to Facebook";
//SUCCESS
}
else if (response.status === 'not_authorized')
{
document.getElementById("message").innerHTML += "<br>Failed to Connect";
//FAILED
} else
{
document.getElementById("message").innerHTML += "<br>Logged Out";
//UNKNOWN ERROR
}
});
};
function Login()
{
FB.login(function(response) {
if (response.authResponse)
{
getUserInfo();
} else
{
console.log('User cancelled login or did not fully authorize.');
}
},{scope: 'email,user_photos,user_videos'});
}
function getUserInfo() {
FB.api('/me', function(response) {
var str="<b>Name</b> : "+response.name+"<br>";
str +="<b>Link: </b>"+response.link+"<br>";
str +="<b>Username:</b> "+response.username+"<br>";
str +="<b>id: </b>"+response.id+"<br>";
str +="<b>Email:</b> "+response.email+"<br>";
str +="<input type='button' value='Get Photo' onclick='getPhoto();'/>";
str +="<input type='button' value='Logout' onclick='Logout();'/>";
document.getElementById("status").innerHTML=str;
});
}
function getPhoto()
{
FB.api('/me/picture?type=normal', function(response) {
var str="<br/><b>Pic</b> : <img src='"+response.data.url+"'/>";
document.getElementById("status").innerHTML+=str;
});
}
function Logout()
{
FB.logout(function(){document.location.reload();});
}
// Load the SDK asynchronously
(function(d){
var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0];
if (d.getElementById(id)) {return;}
js = d.createElement('script'); js.id = id; js.async = true;
js.src = "//connect.facebook.net/en_US/all.js";
ref.parentNode.insertBefore(js, ref);
}(document));
</script>
<div align="center">
<h2>Facebook OAuth Javascript Demo</h2>
<div id="status">
Click on Below Image to start the demo: <br/>
<img src="http://hayageek.com/examples/oauth/facebook/oauth-javascript/LoginWithFacebook.png" style="cursor:pointer;" onclick="Login()"/>
</div>
<br/><br/><br/><br/><br/>
<div id="message">
Logs:<br/>
</div>
</div>
</body>
</html>
Reference:https://developers.facebook.com/docs/reference/javascript/
