Function to generate facebook access token. Requires the https library, an object named keys with app ID and client secret, and facebook-node-sdk

generateAccessToken.js

function generateAccessToken(callback){
  var requestUrl = 'https://graph.facebook.com/oauth/access_token?client_id='+keys.facebook.appID+'&client_secret='+keys.facebook.secret+'&grant_type=client_credentials';
  https.get(requestUrl, function(response){
    response.on('data', function(data){
      var token = data.toString('utf-8').split("access_token=");
      FacebookClient.setAccessToken(token[1]);
      callback();
    });
  }).on('error', function(error){
    console.log(error);
  });
}