W02 d01 iterators with tests

[tgaff]

Adding final exercises with TESTS

• would love some comments here
• I intend to instruct them not to look at the test code

this PR merges into w02-d01-iterators

[nathanallen]

This looks good!

Todo: 1) the exercises folder needs to be moved into a separate lab repo (it has multiple, dependent files / students shouldn't clone the notes repo).

Tips: 1) Make sure to spend a moment reading the MDN documentation together. Don't assume students know how to read it yet. -- e.g. "optional argument" notation (it's not an array!) -- what arguments do the callbacks have: i.e. currentValue, index, array (forEach)

2) Run the tests together, and look at the output together. -- What does it mean to run a test? What's being run? (Students will put method calls inside their js because they assume they need to call the functions explicitly). -- What does a failing test look like / what does a passing test look like?

[tgaff]

Thanks @nathanallen

[tgaff]

You're absolutely right that this should be in another repo. It grew here and I didn't think to transplant it.