Logging

[lrperlmu]

Issue #21 Logging!

Major Changes logger.js :deciduous_tree:

• Connects to firebase database :electric_plug:
• Offers methods for callers (nav and model) to log stuff in the database
  • logTimestamp(event_name) -- records a timestamp and the given event name :stopwatch:
  • logResponses(data) -- takes in a map and writes its keys and values to the database :world_map:

Testing firebase_test.html, firebase_test.js

• scratch file for testing logger.js

Minor Changes demo.html

• add logging stuff :deciduous_tree:
• change title

model.js

• instantiate a Logger in the constructor :deciduous_tree:
• abstract log method that doesn't do anything

dbt_worksheet_model.js

• use the logger to log user responses every time we get them :notebook_with_decorative_cover:
• log(name) method for nav to call to log timestamp of the named event

nav.js

• call model's log method to log timestamp when the app starts :stopwatch:

[lrperlmu]

Rachel -- this code uses a javascript concept that might be new to you: Promises.

You can think of a promise as an object that stores a code snippet that is executing asynchronously, the code's return value, and manages things to do after that code snippet finishes executing.

So, for example, this.signIn is a promise whose code snippet signs in to the database and returns a user credential. You'll find a construction like this appears a couple of times:

        this.signIn.then(credential => {
            // some stuff
        });

That basically means: "Assuming that sign-in is complete and has returned an object called credential, execute "some stuff".

If you want to know more, javascript.info has a (very long winded) section on Promises, and we can also talk about it at tomorrow's meeting.