fun.js

var FBasync = {};

// For each method in the FB library
_.each(FB, function(fn, name) {
  
  // Create an equivalent method in FBasync
  FBasync[name] = function() {
    // Grab the arguments the function was called with
    var _args = arguments;
    
    return new Promise(function(reject, resolve) {
      try {
        // Call the function with our resolver as an additional argument
        fn.apply(FB, Array.prototype.concat.apply(_args, [resolve]));
      } catch(e) {
        reject(e);
      }
    });
  };
});