Chaining Promises Together in JavaScript

Question

I'm working to get my head around promises in JavaScript. From my understanding, I can chain them together. However, there is something that I feel I am missing. Currently, I have an AngularJS app that is using the $localForage module . I need to set an item in local storage. Then, I need to remove an item from local storage. Finally, I need to redirect the user to another page. In an attempt to accomplish this, I've written the following code:

$localForage.setItem('name', 'John Doe')
  .then(function() { return $localForage.removeItem('history'); })
  .then(function() {
    console.log('redirecting the user...');
    $location.url('/views/page-2');
    console.log('should redirect');
  })
;

When this code executes, I see the following in the console:

redirecting the user...
should redirect

However, I never get redirected to /views/page-2 . Interestingly, if I place the $location.url('/views/page-2'); in the first then(...) , I get redirected. For that reason, I feel like there is something that I do not understand about promises.

Am I chaining together properly? Or, am I trying something that I cannot do? If I cannot do this, what is the alternative?

Thank you!

Answer 1

Yeah, the key thing to do is remember to add an error handler in the promise chain. This is accomplished by either adding the second-method callback to the end of your chain as Chris suggested, or ending your chain with a .catch(function(err){console.log(err);}) call.

Errors in a promise chain tend to go into the bitbucket unless you explicitly capture them.