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

Posted by Daniel Carter
Daniel Carter
19,991 Points

I don't know what I need to do to make my code work. Help.

I thought that I need to get into the "personal" part of the customers object to retrieve the hobbies, but apparently that's not working.

app.js 
const customers = [
  {
    name: "Tyrone",
    personal: {
      age: 33,
      hobbies: ["Bicycling", "Camping"]
    }
  },
  {
    name: "Elizabeth",
    personal: {
      age: 25,
      hobbies: ["Guitar", "Reading", "Gardening"]
    }
  },
  {
    name: "Penny",
    personal: {
      age: 36,
      hobbies: ["Comics", "Chess", "Legos"]
    }
  }
];
let hobbies;

// hobbies should be: ["Bicycling", "Camping", "Guitar", "Reading", "Gardening", "Comics", "Chess", "Legos"]
// Write your code below
hobbies = customers
    .map(customer => customer.personal.map(person => person.hobbies))
    .reduce((arr, hobby) => [...arr, ...hobby], []);

1 Answer

Steven Parker
Steven Parker
231,268 Points
Steven Parker
Steven Parker
231,268 Points

You're kind of close, but "personal" is another object so it has no "map" method. But you don't need "map" anyway, you can do this just with "reduce". Here's a few more hints:

  • though the second argument is named "hobby", it represents an entire "customers" object
  • each object will have another object named "personal" inside it
  • the "personal" sub-object will have an array named "hobbies" in it