es6-iterators-generators.js

// ITERATORS
// Exemplo de modificar o iterator para adicionar uma string 'is Sexy'
// sempre que utilizamos um for of loop

let myArray = ['Antonio', 'Toze', 'Toninho'];
 
myArray[Symbol.iterator] = function() {
    let index = -1;
    const length = this.length;
    const arr = this;
    return {
        next: function() {
            index++;
            return {
                done: index > length - 1 ? true : false,
                value: arr[index] + ' is Sexy'
            };
        }
    };
}
 
//-for..of loop;
for (let element of myArray) {
    console.log(element);
}

// "Antonio is Sexy"
// "Toze is Sexy"
// "Toninho is Sexy"

// ITERATOR COSTUM
// For of loop through persons hobbies

const person = {
  name: 'Antonio',
  hobbies: ['surf', 'gaming', 'coding'],
  [Symbol.iterator]: function() {
    let index = 0
    const hobbies = this.hobbies
    return {
      next: function () {
        const hobbie = hobbies[index]
        index += 1
        return {
           done: index > hobbies.length ? true : false,
           value: hobbie
        }
      }
    }
  }
}

for (let hobby of person) {
  console.log(hobby)
}

// "surf"
// "gaming"
// "coding"

// GENERATORS
// generator function marked with *
// generates iterator

function* gen(end) {
  for (let i = 0; i < end; i++) {
    try { 
      yield i
    } catch (err) {
      console.log(`error message - ${err}`)
    }
  }
}

const it = gen(3)

console.log(it.next())
console.log(it.throw('MonkaS'))
console.log(it.next())
console.log(it.next())

/*
 
[object Object] {
  done: false,
  value: 0
}
"error message - MonkaS"
[object Object] {
  done: false,
  value: 1
}
[object Object] {
  done: false,
  value: 2
}
[object Object] {
  done: true,
  value: undefined
}

*/