Week 2 Review

A review of topics chosen by you during week 2! (rhyming intentional) #Objectives

• Understand the return statement within a function
• Be comfortable searching for and reading Docs
• Understand the use of a callback within iterators
• Be comfortable with reimplementing your own iterator (map)
• Understanding why we use the TDD style
• Be comfortable reading tests written with Mocha / Chai
• Understand "Setup, Exercise, Verify"
• Understand how to read your errors

 

##Docs, Return, & Iterators ###Basic Definitions

• Docs (Documentation): When we reference the docs, we are referring to the documentation of a given language, library, framework, etc...
  • Javascript: https://developer.mozilla.org/en-US/docs/Web/JavaScript
  • Bootstrap: http://getbootstrap.com/getting-started/
• Iterator: An Iterator is a function that knows how to access items from a collection one at a time, while keeping track of its current position within that sequence.

###Return #####So... why do we use return? Here it is important for us to first think about the underlying environment we are using the return statement in: a function.

When a function is invoked, it begins execution with the first statement , and ends when it hits the } that closes the function body. That causes the function to return control to the part of the program that invoked the function.

Now, here's where it gets tricky, a function in javascript always returns a value. It just doesn't implicitly return the last line of the function like some other nifty languages ::cough:: ruby ::cough, cough:: So, in javascript, if the return value is not specified, then undefined is returned. Thus, we designate a return statement inside our function to return the value we would like the function to pass to the program that invoked it.

#####But what does it actually do? A return is a statement that we use within functions to cause a function to return early. When return is executed, the function returns immediately without executing the remaining statements. **

#####Wait...didn't we use two returns that one time? We did. Let's parse through this bad boy together.

function tripler (numbers) {
    return numbers.map(function(num) {
      return num * 3;
    });
  }

###Docs & Iterators So we just looked at map from a use case standpoint, lets give reimplementing it a whirl.

Let's take a look at the docs together. To do this, we've provided a link below that outlines a good workflow for finding some docs...

• Click me!

#####Steps:

1. Pair with the person next to you
2. Discuss your understanding of the documentation we just read
3. Use a pencil and paper // whiteboard marker to psuedo-code what you're about to do
4. Write some code. Have one pilot (typing) & one navigator (observe,comment,debug) - Remember your etiquette - don't interrupt a thought, don't interrupt a line of code being written (typos can be fixed at the end), use good tone, every idea merits discussion.