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JavaScript JavaScript Array Iteration Methods Combining Array Methods Nested Data and Additional Exploration

Samuel Kleos
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.a{fill-rule:evenodd;}techdegree
Samuel Kleos
Front End Web Development Techdegree Student 12,719 Points

Is this approach okay? #flatten #reduce #map

Hey, I reduced it first because I wanted to access a flattened array of title objects.

// flatten favouriteBooks objects and map over objects to extract title strings.
const titles = users
    .reduce((arr, user) => [...arr, ...user.favoriteBooks], [])
    .map(book => book.title)
console.log(titles);

// DATA SOURCE

const users = [
  {
    name: 'Samir',
    age: 27,
    favoriteBooks:[
      {title: 'The Iliad'},
      {title: 'The Brothers Karamazov'}
    ]
  },
  {
    name: 'Angela',
    age: 33,
    favoriteBooks:[
      {title: 'Tenth of December'},
      {title: 'Cloud Atlas'},
      {title: 'One Hundred Years of Solitude'}
    ]
  },
  {
    name: 'Beatrice',
    age: 42,
    favoriteBooks:[
      {title: 'Candide'}
    ]
  }
];

1 Answer

Steven Parker
Steven Parker
229,921 Points

Sure, it doesn't matter which order you use the reduce and map, you still get the same result.   :+1:

But … you must define users before you can reference it to create titles. That order is important.