const array = [
  {id: 12, name: 'toto'},
  {id: 12, name: 'toto'},
  {id: 42, name: 'tutu'},
  {id: 12, name: 'toto'},
];

const id = 12;
const count = array.filter((obj) => obj.id === id).length;

console.log(count);