Mastering JavaScript Promises

Unbinds and its solution

When you are working with methods, instead of simple functions, it's highly likely that you can easily run into the common problems where passing a method to another function—such as Q.nfcall—unbinds the method from its owner. Q has to offer its services here too so that you can avoid this, by adopting any of these two ways:

• Use Function.prototype.bind()
• Use these methods provided by Q:

  return Q.ninvoke(redisClient, "get", "user:1:id"); // node invoke
  return Q.npost(redisClient, "get", ["user:1:id"]); // node post

There is yet another way you can create reusable wrappers, using:

• Q.denodeify:

  //using Q.denodeify
  var readFile = Q.denodeify(FS.readFile);
  return readFile("foo.txt", "utf-8");

• Q.nbind:

  // Q.nbind var redisClientGet ...