meteor__microscope/facebook.js

// Fonction hypothétique...
function getFacebookLikeCount() {}

currentLikeCount = 0;

Meteor.setInterval(function () {
  var postId;

  if (Meteor.user() && postId === Session.get('currentPostId')) {
    getFacebookLikeCount(Meteor.user(), Posts.find(postId).url, function (err, count) {
      if (!err) {
        currentLikeCount = count;
      }
    });
  }
}, 5 * 1000);

// Insert in "post_item.js".
Template.postItem.helpers({
  likeCount: function () {
    return currentLikeCount;
  }
});