Can I do a binary search on an array of objects?

I am currently learning how to use searching and sorting algorithms and I am running into issues with a binary search on an array of objects of customers’ data. The array of customers is sorted by first and last name.

The goal is to find a customer’s email and return the index.

The data looks like:

[
  {
    "username": "Maude.Torp",
    "email": "[e-mail]",
    "address": {
      "street": "Rowe Fields",
      "suite": "Suite 231",
      "city": "Tiannamouth",
      "zipcode": "07584-6653",
      "geo": { "lat": "75.0283", "lng": "-17.1824" }
    },
    "phone": "795-827-5446 x18366",
    "website": "nico.com",
    "company": {
      "name": "Champlin, Feest and Barrows",
      "catchPhrase": "Object-based user-facing orchestration",
      "bs": "transition integrated content"
    },
    "firstName": "Maida",
    "lastName": "Feeney"
  },
  ...
]

My binary search function looks like:

function searchByEmail(email, customers) {
  let start = 0;
  let end = customers.length - 1;

  while (start <= end) {
    let middle = Math.floor((start + end) / 2);

    if (customers[middle] === email) {
      return middle;
    } else if (customers[middle] < email) {
      start = middle + 1;
    } else {
      end = middle - 1;
    }
  }
  return -1;
}

On a sorted array of numbers I am able to return the index of the desired key.

let customers = [1, 10, 45, 56, 66, 567]
...
console.log(searchByEmail(66, customers))

// --> 4

When I look through this array of objects I only return -1. How do I change this algorithm to work for objects within arrays?

Answer

You should be able to binary search the customer array, provided that it’s ordered by customer email.

Change the code up a bit to compare the email instead of the entire object, accessing the email property of the object.

function searchByEmail(email, customers) {
  let start = 0;
  let end = customers.length - 1;

  while (start <= end) {
    let middle = Math.floor((start + end) / 2);

    // NOTE the ".email" part added
    if (customers[middle].email === email) {
      return middle;
    } else if (customers[middle].email < email) {
      start = middle + 1;
    } else {
      end = middle - 1;
    }
  }
  return -1;
}