Promise Chain Example

PromiseExample.js

/* 
  So what I would like to happen is app
  is initialize in componentDidMount(),
  if we are to recieve an error, have the
  initializeApp() function cancel out the
  entire promise chain.
  
  Ideally, the promise child is able to either
  cancel execution of the promise and navigate to the
  right place by default, or hand off the navigation to
  the parent.
  
  We could have a promise chain of
  Parent, child1 -> child2, and we could have several
  default behaviors. Basically we control the entire
  flow of the app through streams, similar to functional
  programming languages I suppose.
  
  There's already some work on it, but I have yet to investigate it.
*/

// Inside of React component
componentDidMount() {
  initializeApp().then(() => {
    // Handle desired navigation here
    
    // This gets called despite errors in
    // initializeApp()
  });
}

// AppActions.js
export async function initializeApp() {
  try {
    const creds = await getKeychainCreds();
    const id = AsyncStorage.getItem('USER_ID');
    
    await verifyCredentials(creds);
    await userAccountVerified(id);
  } catch(e) {
    if(e.type === "USER_NOT_VERIFIED") {
      // Navigate to User
    }
    if(e.type === "CREDENTIALS") {
      // Navigate to login route
    }
    // else do nothing
  }
}