Remove object, with a common property, from array

Question

Is there a way to remove an object from an array if a single property in that object is found in another object in that array?

const arr = [{
  car: 'bmw',
  notimportant: 'bla bla',
},{
  car: 'audi',
  notimportant: 'bli bli',
},{
  car: 'bmw',
  notimportant: 'ble ble',
},{
  car: 'golf',
  notimportant: 'blo blo',
}]

Also I would like to add a counter of how many duplicates there were

Expected result:

[{
  car: 'bmw',
  count: 1,
  notimportant: 'bla bla',
},{
  car: 'audi',
  count: 0,
  notimportant: 'bli bli',
},{
  car: 'golf',
  count: 0,
  notimportant: 'blo blo',
}]

Answer 1

You can use Array#reduce with an object to store the values for each car.

const arr = [{
  car: 'bmw',
  notimportant: 'bla bla',
},{
  car: 'audi',
  notimportant: 'bli bli',
},{
  car: 'bmw',
  notimportant: 'ble ble',
},{
  car: 'golf',
  notimportant: 'blo blo',
}];
const res = Object.values(arr.reduce((acc,curr)=>{
  ++(acc[curr.car] = acc[curr.car] || {...curr, count: -1}).count;
  return acc;
}, {}));
console.log(res);