Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

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

Samuel Kleos
seal-mask
.a{fill-rule:evenodd;}techdegree
Samuel Kleos
Front End Web Development Techdegree Student 13,307 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
231,172 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.