isacjunior

const users =
  [
    {name: {first: 'Bruce', last: 'Wayne'}, age: 26, sales: 2314},
    {name: {first: 'Alvaro', last: 'Angelos'}, age: 55, sales: 1668},
    {name: {first: 'Denese', last: 'Dossett'}, age: 29, sales: 9248},
    {name: {first: 'Douglas', last: 'Denney'}, age: 49, sales: 5058},
    {name: {first: 'Earline', last: 'Erickson'}, age: 19, sales: 18876},
    {name: {first: 'Herman', last: 'Hazell'}, age: 25, sales: 2746},
    {name: {first: 'Homer', last: 'Hirth'}, age: 26, sales: 474},
    {name: {first: 'Hwa', last: 'Heidt'}, age: 32, sales: 9607}

isacjunior

const filterAgeEx1 = users.filter(function(user) {
  return user.age > 50
})

isacjunior

const filterAgeEx2 = users.filter(user => user.age > 50)

isacjunior

function hasThanMore50(user) {
  return user.age > 50
}

const filterAgeEx3 = users.filter(hasThanMore50)

isacjunior

function hasThanMore(user, age) {
  return user.age > age
}

const filterAgeEx4 = users.filter(user => hasThanMore(user, 50))

isacjunior

function filter(array, test) {
  const passed = []
  for (var i = 0; i < array.length; i++) {
    if(test(array[i]))
      passed.push(array[i])
  }
  return passed
}

const filterAgeEx5 = filter(users, user => user.age > 50)

isacjunior

function filterUserHasThanMore50(array) {
  const passed = []
  for (var i = 0; i < array.length; i++) {
    if(array[i].age > 50)
      passed.push(array[i])
  }
  return passed
}

isacjunior

const numbers = [3, 1, 6]

function sumNumbers(numbers) {
  let result = 0
  for(let i = 0; i < numbers.length; i++) {
    result += numbers[i]
  }
  return result
}

isacjunior

const numbers = [3, 1, 6]
const sum = numbers.reduce((sum, item) => sum + item)

console.log(sum) // 10

isacjunior

const sumSales = (previusSales, nextSales) => previusSales + nextSales
const bySales = (item) => item.sales
const totalSales = users.map(bySales).reduce(sumSales)

console.log(totalSales) // 49991