davidystephenson

// Type definition for wand using tuple
type Wand = [core: string, length: number, material: string]

// Enum for house names
enum House {
  Gryffindor = 'Gryffindor',
  Slytherin = 'Slytherin'
}

// Type for character

davidystephenson

type Message = number | true | 'goodbye'

const message1 = 100 

const message2 = true

const message3 = 'goodbye'

const response: Message[] = [true, 'goodbye', true, 100, 42]
const firstResponse = response[0]

davidystephenson

<script>
  const localCounter = sessionStorage.getItem('counter')
  console.log('savedCounter:', localCounter)
  console.log('typeof savedCounter:', typeof localCounter)

  const counter = Number(localCounter)
  const newCounter = counter + 1
  const newCounterString = String(newCounter)
  sessionStorage.setItem('counter', newCounterString)
</script>

davidystephenson

<script>
  const localCounter = localStorage.getItem('counter')
  console.log('savedCounter:', localCounter)
  console.log('typeof savedCounter:', typeof localCounter)

  const counter = Number(localCounter)
  const newCounter = counter + 1
  const newCounterString = String(newCounter)
  localStorage.setItem('counter', newCounterString)
</script>

davidystephenson

<script>
  console.log('before')
  async function main () {
    const uploadData = { message: 'ready' }
    const uploadJson = JSON.stringify(uploadData)
    const init = { body: uploadJson, method: 'POST' }
    // { body: JSON.stringify(uploadData), method: 'POST' }
    const dogResponse = await fetch('https://dog.ceo/api/breeds/image/random', init)
  }
  main() // asynchronous / non-blocking

davidystephenson

<img id="dog" width="500"/>

<script>
  console.log('before')
  async function main () {
    console.log('starting dog download...')
    const dogResponse = await fetch('https://dog.ceo/api/breeds/image/random')
    const dogData = await dogResponse.json()
    console.log('dogData', dogData)

davidystephenson

<script>
  // First log 'start'
  // Then log "starting alpha"
  // Then, sleep for 2 seconds
  // Then, log 'alpha'
  // Then, log "starting beta"
  // Then, 4 seconds later, log beta
  // Then, log "starting gamma"
  // Then, 1 second later log gamma
  // Then, log "starting delta"

davidystephenson

<script>
  // First log 'start'
  // Then log "starting alpha"
  // Then, sleep for 2 seconds
  // Then, log 'alpha'
  // Then, log "starting beta"
  // Then, 4 seconds later, log beta
  // Then, log "starting gamma"
  // Then, 1 second later log gamma
  // Then, log "starting delta"

davidystephenson

<script>
  // First log 'start'
  // Then log "starting alpha"
  // Then, 2 seconds later, log alpha
  // Then, log "starting "beta"
  // Then, 4 seconds later, log beta
  // Then, log "starting gamma"
  // Then, 1 second later log gamma
  // Then, log "starting delta"
  // Then, 3 seconds later log delta

davidystephenson

const x = 'hello!!!'
console.log(x)
const y = 42

type List = [first: string, second: string, third: number] 

const list: List = ['a', 'b', 3]

function describe <T> (value?: T) {
  console.log('The value is:', value)