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/**
 * check if vals are objects
 * if so. copy that object (deep copy)
 * else return the value
 */

function deepCopy(obj) {
  const keys = Object.keys(obj);
  const newObject = {};
  for (let i = 0; i < keys.length; i++) {

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SQL

Log into database: mysql [db_name]

View a table: SELECT * FROM table_name;

Update a record in a table:

UPDATE [table_name] SET [table_column] = NOW() WHERE id = 1;

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// In JS `!!` can be used to convert any value to a boolean
// Similar to using the Boolean() function

(function() {
  var foo = 'foo';
  console.log(typeof foo);

  var bool = !!foo;
  console.log(typeof bool);
  console.log(bool);

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// `bind` and `this`
let dog = {
  sound: 'woof',
  talk: function() {
    console.log(this.sound);
  }
}

dog.talk(); // => 'woof'

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// Anonymous function:
// Ex.1
(function() {
  // We keep these variables private inside this closure scope
  var myGrades = [93, 95, 88, 0, 55, 91];
  var average = function() {
    var total = myGrades.reduce(function(accumulator, item) {
	  return accumulator + item;
    }, 0);
	return 'Your average grade is ' + total / myGrades.length + '.';

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// JS has 5 data types that are assigned by value:
// `Boolean`, `String`, `Number`, `null`, `undefined` (primitives)
// JS has 3 data types that are assigned by reference:
// `Array`, `Function`, `Object` (objects)

var x = 1, y = '1', z = undefined;

// When we assign these vars to other vars we copy the value to the new var

var a = x, b = y, c = z;

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// Observer Pattern Notes
// The instance (subject) maintans a collection of objects (observers)
// The instance notifies the objects when changes to the state occur

class Observable {
  // each instance starts with an empty array of observers that react to state changes
  constructor() {
    this.observers = [];
  }
  

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// Lifecycle phases:

// Initiialization: Defaults & initial values for `this.props` and `this.state`
// `getDefaultProps()` is called once and cached when the class is created
// We can't rely on `this.props` in `getDefaultProps()`
// `getInitialState()` is invoked once right before the mounting phase

var Counter = React.createClass({
  getDefaultProps: function() {
    console.log('getDefaultProps');

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// Passing a value of 0 to the `setTimeout` method deffers the callback to the end of the stack or until the stack is clear
setTimeout(function() {
  console.log('test');
}, 0);
// `setTimoeout` is not a guaranteed time to exucution, it's a minimum time to execution
// Passing a value of 0 to `setTimeout` doesn't run the code immediately, it runs the code as soon as the stack is clear (nextish)
// The event loop pushes any deffered executions in the task/callback que only after the stack is clear
// The stack can continue to run while waiting for a request from the web API
// The browser can't perform a render while code is running on the stack
// Avoid putting slow/heavy duty code on the stack because it prevents browsers from rendering the UI

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// Sessions

// A place to store data that you want access to across requests.
// Each user that visits your site has a unique session
// Sessions can be used to store and access user data as they access your application
// Sessions allow a web app to store state

// Simple session in Express:
import express from 'express';
import session from 'express-session';