gistfile1.txt

const o = { message: 'hi', count: 5 }

// type Output = {
//   message: string
//   count: number
// }
type Output = typeof o

const results = []

function getValue <T extends keyof Output> (data: Output, key: T) {
  console.log(`I will get the ${key} from the data`)
  const value = data[key]
  results.push(value)
  return value
}

const message = getValue<'message'>(o, 'message')
function capitalize (text: string) {
  console.log(text.toUpperCase())
}
capitalize(message)

const count = getValue(o, 'count')
function fix (number: number) {
  console.log(number.toFixed(2))
}
fix(count)