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Object nesting ​

Creating nested objects ​

Some more complex data structures can be created by nesting lists and objects inside other objects.

js
const user = {
  name: 'Jane Doe',
  email: 'jane.doe@example.com',
  address: {
    street: '123 Main St',
    city: 'Sometown',
    county: 'Anyshire',
    postcode: 'AB1 2CD'
  },
  borrowedBooks: [
    {
      id: 1,
      title: "The Handmaid's Tale",
      author: 'Margaret Atwood',
      year: 1985,
      isbn: '9780099740919'
    }
  ]
}

Accessing nested objects ​

We can chain together the property names to access the nested object's properties.

js
console.log(user.address.street)
console
123 Main St

Accessing nested arrays ​

Similarly, for nested arrays we can write:

js
console.log(author.books[0].title) // 'The Handmaid's Tale'
console
The Handmaid's Tale

Optional chaining ​

This is a nice syntax for checking if a property exists before trying to access it.

js
function logFirstBookTitle(user) {
  return user.borrowedBooks[0]?.title
}