helpers.js

// Get the account service to use for the user's avatar
// Priority: Twitter > Facebook > Google > GitHub > Instagram > Linkedin
getService = function (user) {
  var services = user && user.services || {};
  var customProp = user && Avatar.options.customImageProperty;
  if (customProp && getDescendantProp(user, customProp)) { return 'custom'; }
  var service = _.find(['twitter', 'facebook', 'google', 'github', 'instagram', 'linkedin'], function(s) { return !!services[s]; });
  return service || 'none';
};

getGravatarUrl = function (user, defaultUrl) {
  var gravatarDefault;
  var validGravatars = ['404', 'mm', 'identicon', 'monsterid', 'wavatar', 'retro', 'blank'];

  // Initials are shown when Gravatar returns 404.
  if (Avatar.options.fallbackType !== 'initials') {
    var valid = _.contains(validGravatars, Avatar.options.gravatarDefault);
    gravatarDefault = valid ? Avatar.options.gravatarDefault : defaultUrl;
  }
  else {
    gravatarDefault = '404';
  }

  var options = {
    // NOTE: Gravatar's default option requires a publicly accessible URL,
    // so it won't work when your app is running on localhost and you're
    // using an image with either the standard default image URL or a custom
    // defaultImageUrl that is a relative path (e.g. 'images/defaultAvatar.png').
    default: gravatarDefault,
    size: 200, // use 200x200 like twitter and facebook above (might be useful later)
    secure: true
  };

  var emailOrHash = getEmailOrHash(user);
  return Gravatar.imageUrl(emailOrHash, options);
};

// Get the user's email address or (if the emailHashProperty is defined) hash
getEmailOrHash = function (user) {
  var emailOrHash;
  if (user && Avatar.options.emailHashProperty && !!getDescendantProp(user, Avatar.options.emailHashProperty)) {
    emailOrHash = getDescendantProp(user, Avatar.options.emailHashProperty);
  }
  else if (user && user.emails) {
    emailOrHash = user.emails[0].address; // TODO: try all emails
  }
  else {
    // If all else fails, return 32 zeros (trash hash, hehe) so that Gravatar
    // has something to build a URL with at least.
    emailOrHash = '00000000000000000000000000000000';
  }
  return emailOrHash;
};