atelier-01.js

const wilder = {
  firstName: 'Clément',
  lastName: 'Denis',
  age: 30,
  isExperienced: true,
}

const showWilder = (w) => {
  const firstName = w.firstName.toLowerCase()
  const lastName = w.lastName.toUpperCase()
  return `${firstName} ${lastName} ${w.age}`
}

const wilderSaruman = {
  firstName: 'Saruman',
  lastName: 'Pat',
  age: 89,
  isExperienced: true,
}

const wilderList = [
  wilder,
  wilderSaruman,
  {
    firstName: 'Pépito',
    lastName: 'Rodrigez',
    age: 12,
    isExperienced: false,
  },
]

const showAllWilders = list => list.forEach(showWilder)

const wildersAverageAge = list => {
  let total = 0
  list.forEach(w => total = total + w.age)
  return total / list.length
}


const over30 = list => {
  const filteredList = []
  list.forEach(w => {
    if (w.age > 30) {
      filteredList.push(w)
    }
  })
  return filteredList
}