Skipping promise chain after handling error

Question

Using the https://github.com/kriskowal/q library, I\'m wondering if it\'s possible to do something like this:

// Module A

function moduleA_exportedFunction(         


        

Answer 1

Inspired by Benjamin Gruenbaum's comments and answer - if I was writing this in synchronous code, I would make moduleA_exportedFunction return a shouldContinue boolean.

So with promises, it would basically be something like this (disclaimer: this is psuedo-code-ish and untested)

// Module A

function moduleA_exportedFunction() {
  return promiseReturningService().then(function(serviceResults) {
    if (serviceResults.areGood) {
      // We can continue with the rest of the promise chain
      return true;
    }
    else {
      performVerySpecificErrorHandling();
      // We want to skip the rest of the promise chain
      return false;
    }
  });
}

// Module B

moduleA_exportedFunction()
  .then(function(shouldContinue) {
    if (shouldContinue) {
      return moduleB_promiseReturningFunction().then(moduleB_anotherFunction);
    }
  })
  .fail(function(reason) {
    // Handle the reason in a general way which is ok for module B functions
    // (And anything unhandled from module A would still get caught here)
  })
  .done()
;

It does require some handling code in module B, but the logic is neither specific to module A's internals nor does it involve throwing and ignoring fake errors - mission accomplished! :)