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JavaScript JavaScript Array Iteration Methods Combining Array Methods Nested Data

Samuel Fortunato
Samuel Fortunato
20,229 Points
Posted by Samuel Fortunato
Samuel Fortunato
20,229 Points

JavaScript Array Iteration Methods Last Exercise = Stumped

The last exercise in this course has got me.

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

This is what I have so far:

hobbies = customers
  .reduce((hobbiesList, customer) => customer.personal.hobbies.map(hobby => hobby));

Not working. Don't get it. :(

1 Answer

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

You seem to be heading in the right direction. Here's a few hints:

  • that "map" function isn't doing anything, you can remove it entirely
  • you might need to give "reduce" an additional argument for an initial value
  • the function needs to use both arguments
  • the function should do something that combines two arrays together into one
Samuel Fortunato
Samuel Fortunato
20,229 Points
Samuel Fortunato
Samuel Fortunato
20,229 Points

Ok, I've gotten farther. My code is now this:

hobbies = customers
  .reduce((hobbiesList, customer) => hobbiesList + customer.personal.hobbies, []);

And my output is now this, according to the code challenge:

"Bicycling,CampingGuitar,Reading,GardeningComics,Chess,Legos"

Seems like I just have to get each array item individually and not grab the whole thing? Why isn't reduce() grabbing each array item individually? I thought that's what it did?

Steven Parker
Steven Parker
229,732 Points
Steven Parker
Steven Parker
229,732 Points

You're really close now! You're successfully combining all the individual hobbies into a string, so now you only need to change it so that the combination is another array. Hint: the "spread" operator ("...") might be useful.