ES6 The Right Parts

Arrow Functions
Introduction
The Arrow Function
  What is arrow function? How is it useful?
  => suppose to replace "function" keyword
  foo = () => 2; // or foo = x => 2;

  function foo() {
    return 2;
  } 

  but arrows can have variations - and this can be a problem
  other than reability 
Arrow Function Variations
  () => 3;
  x => 3;
  _ => 3; // warning - Do not user - Can be confusing or cause error
  Three things to do with parameters - all must be enclosed with parenthesis 
    1. default values
    2. spread
    3. destructuring
  
  (...x) apply the gather operator on parameters 
  (x,y) => 3; // multiple parameters need to be enclosed in parenthesis

  x => {try {3;} catch(e) {} } // now need to use "return" keyword to return value
  x => {return 3;} // like this

  x => ({y: x})  // return a JSON object

  arrow function are anonymous 
    - cannot be recusive 
    - cannot reference self easily 
    - hard to debug with anonymous functions

  Name inferencing 
  var foo = x => 3;
  foo.name; // "foo"
  ...but it dos not work when arrow function is passed in as argument
  foo( x => 3 )
 
Promises and This
  p.then( function(v) {return v.id} )
  p.then( v => v.id )
  if v is null then exception will be thrown from anonymous function
  - it will be difficult to debug through stack trace 
  
  A better way might be naming the function:
  p.then( function extractId(v) {return v.id} ) 
  // the code is more readable and easier to debug through stack trace 

Exercise 0: The Arrow Function
Exercise 0 Solution

Block Scope
Let vs. Var
Closures and Explicit Blocks
Const
When to Use Const
Exercise 1: Variable Scoping
Exercise 1 Solution

Default Values and the Gather/Spread Operator
Default Values
Lazy Expressions
Gather and Spread Operators, Part 1
Gather and Spread Operators, Part 2
Using the Gather and Spread Operators
Exercise 2
Exercise 2 Solution
Babel

Destructuring
Audience Q&A: TypeScript vs. JavaScript
Array Destructuring
Destructuring and Default Values
Dumping Variables
Nested Array Destructuring
Object Destructuring
Nested Object Destructuring
Destructuring and Function Parameters
Advanced Destructuring
Exercise 3
Exercise 3 Solution

Template Strings
Concise Properties and Methods
Template Strings
Tag Functions
Exercise 4
Exercise 4 Solution

Symbols, Iterators, and Generators
Symbols
Well-known Symbols
Iterators
Creating a Custom Iterator
Generators
Computed Generator Methods
Exercise 5
Exercise 5 Solution

Ranges
Optimizing Code for the Reader