I love Promises. We use it in all our projects. It can be used with AngularJS, jQuery or even Vanilla Javascript. I will not explain about Promises basics here, if you are not familiar with Promises, take a look here and here.

The interesting stuff starts when there are several serial actions (sometimes with different operations between them).

Without chaining, you will quickly find yourself writing a "Promise Soup" (all examples are in jQuery. It is pretty much the same for all other options, with slight syntax differences):

Wow. This is exactly what Promises intended to prevent in the first place!

chaining promises

For this simple example, chaining should be pretty straightforward:

Cool. This is much cleaner and easier to read.

Now, for a complete example (jsBin):

The really cool things here are:

• You can listen to fail/error events in one place. An error will stop the chaining and get to the closest fail statement. (jsBin)
• Resolved data will be passed to chained function.

Disadvantages:

• Passing data between "getA" to "getC" must go via "getB" (or a global object)
• Harder to implement when there are conditional calls to serial methods ("getB" is called only if some condition applies in "aData", for example)

That's it. Keep on chaining!