Can you merge the values between two arrays of objects by counting them and combining them into a single array?

I'm faced with an array conundrum

categories: [
  {
   name: 'category1',
   items: 0,
  },
  {
   name: 'category2',
   items: 0,
  },
  {
   name: 'category3',
   items: 0,
  },
]

And then there's this separate array

items: [
  {
   name: 'Item1',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="caa8a6aba8a6ab8aada7aba3a6e4a9a5a7">[email protected]</a>',
   category:'category1'
  },
  {
   name: 'Item2',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="88e4e9e4e9e4e9c8efe5e9e1e4a6ebe7e5">[email protected]</a>',
   category:'category2'
  },
  {
   name: 'Item3',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="97f8f8f8f8d7f0faf6fefbb9f4f8fa">[email protected]</a>',
   category:'category2'
  },
]

Now, I'm struggling with determining the count of items in each category. I've attempted using map and filter functions, but so far, no luck.

My Expectation

I anticipate a function to update the categories array accordingly with the correct item count.

javascriptarraysjavascript-objects

Answer №1

Optimize your code by utilizing .map and .filter:

const divisions = [
  {
   title: 'division A',
   employees: 0,
  },
  {
   title: 'division B',
   employees: 0,
  },
  {
   title: 'division C',
   employees: 0,
  }
]

const employees = [
  {
   name: 'Alice',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="1236232324232326993539333c3f623f3133">[email protected]</a>',
   division: 'division A'
  },
  {
   name: 'Bob',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="1e737c737c737c4d6a707c7462616c7072">[email protected]</a>',
   division: 'division B'
  },
  {
   name: 'Charlie',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="2f424242423f68464a4256470a464a48">[email protected]</a>',
   division: 'division B'
  }
]

console.log(
    divisions.map((division) => {
        division.employees = employees.filter((employee) => employee.division === division.title).length;
        return division;
    })
);

Answer №2

Consider this approach where a deptCount object is created from the persons array. It then iterates through the departments array, updating the persons property. This method may offer better efficiency compared to nested loop solutions, although it is unlikely to make a significant difference unless dealing with a large number of people and departments.

const departments = [
  {
   name: 'smthg',
   persons: 0,
  },
  {
   name: 'anotherone',
   persons: 0,
  },
  {
   name: 'and anotherone',
   persons: 0,
  },
]

const persons = [
  {
   name: 'John',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="8ceee0edeee0edccebe1ede5e0a2efe3e1">[email protected]</a>',
   department:'smthg'
  },
  {
   name: 'Ninja',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="28444944494449684f45494144064b4745">[email protected]</a>',
   department:'anotherone'
  },
  {
   name: 'Tom',
   email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="f699999999b6919b979f9ad895999b">[email protected]</a>',
   department:'anotherone'
  },
]

const deptCounts = persons.reduce((acc, el) => {
  acc[el.department] = (acc[el.department] || 0) + 1;
  return acc;
}, {});

departments.forEach(dept => {
  dept.persons = (deptCounts[dept.name] || 0);
});

console.log(departments);

Answer №3

Utilizing the updateDepartments() function triggers an update to the departments variable by incorporating the latest persons count

const departments = [
  {
    name: 'something',
    persons: 0,
  },
  {
    name: 'another',
    persons: 0,
  },
  {
    name: 'and another',
    persons: 0,
  },
]

const persons = [
  {
    name: 'Emily',
    email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="6e0c020f0c020f2e09030f0702400d0103">[email protected]</a>',
    department:'something',
  },
  {
    name: 'Samurai',
    email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="3d515c515c515c7d5a505c5451135e5250">[email protected]</a>',
    department:'another',
  },
  {
    name: 'Lisa',
    email: '<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="472828282807202a262e2b6924282a">[email protected]</a>',
    department:'another',
  },
]

function updateDepartments() {
  persons.forEach(person => {
    const index = departments.findIndex(department => department.name === person.department)
    if (index) {
      departments[index].persons++
    }
  })
}

updateDepartments()

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