Array of specific Object in Javascript

I am working on a Vue.js application where I am managing a list of clients. I want to ensure I am applying Object-Oriented Programming (OOP) concepts by using a Client class for each client in my array. However, my clients array is currently just a plain array of objects, not instances of a Client class.

Here is what I am trying to achieve:

I want to fetch the client data from an API.
After fetching, I would like to instantiate a Client class for each client in the response data, so that each client has methods and properties defined in the class.
Currently, my clients array is just an array of plain JavaScript objects, not instances of the Client class.
Here’s what I have so far:

export default class Client {
  constructor(id, cin, nom, prenom) {
    this.id = id;
    ****

  }

}

Fetching data and mapping it to the Client class:

import Client from './Client';
import clientService from '../services/clientService';

export default {
  data() {
    return {
      clients: [],
    };
  },
  created() {
    this.fetchClients();
  },
  methods: {
    fetchClients() {
      clientService.findAll()
        .then(response => {
          // Mapping the raw data to instances of the Client class
          this.clients = response.data.map(clientData => new Client(clientData.id, clientData.cin, clientData.nom, clientData.prenom));
        })
        .catch(error => {
          console.error('Error fetching clients:', error);
        });
    },
  },
};

After calling this.clients = response.data.map(...), I expected the clients array to contain instances of the Client class. However, it seems to be a simple array of plain JavaScript objects.

In java for example , I can specify the type of instances that I will be storing inside my array. In JavaScript, we typically don’t enforce class-based structures for simple data models.

I mean why not :

clients: [] of Clients

Sorry if the question sounds dumb because everything is working fine , but I need some clarification.