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JavaScript JavaScript Array Iteration Methods Combining Array Methods Nested Data

Fred Tarbox
PLUS
Fred Tarbox
Courses Plus Student 17,110 Points
Posted by Fred Tarbox
Fred Tarbox
Courses Plus Student 17,110 Points

Cannot read property 'Symbol(Symbol.iterator)' of undefined

This code works in Codepen but not here

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.reduce((a, personal) => { [ ...a, ...personal.hobbies];}, []);

//console.log(hobbies);

1 Answer

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

I get the exact same error in Codepen, as I would expect.

There's two syntax issues:

  • when defining an arrow function with brackets, you must return the result
  • "hobbies" is not a direct property of a "customers" array item (which is what "personal" represents)
Fred Tarbox
Fred Tarbox
Courses Plus Student 17,110 Points
Fred Tarbox
Fred Tarbox
Courses Plus Student 17,110 Points

Here's my exact code in Codepen:

hobbies = customers.reduce(function(prev, curr) { return [ ...prev, ...curr.hobbies]; }, []); console.log(hobbies);

and here's the result:

["Bicycling", "Camping", "Guitar", "Reading", "Gardening", "Comics", "Chess", "Legos"]

I put this same code into the Challenge Task and get the error

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

That's a bit different from what you show above, but it only resolves one of the two issues, and still produces the same error instead of that result on Codepen.

Since "hobbies" is not a direct property of a "customers" array item, you need to access it via the "personal" property ("curr.personal.hobbies").