WeakMap

const { inspect } = require('util');

let visitsCountMap = new WeakMap(); // Menyimpan daftar user

function countUser(user) {

let count = visitsCountMap.get(user) || 0;

visitsCountMap.set(user, count + 1);

}

let jonas = { name: "Jonas" };

countUser(jonas); // Menambahkan user "Jonas"

jonas = null; // Data object "Jonas" dihapus

// delay dibutuhkan untuk menunggu garbage collector bekerja

setTimeout(function() {

console.log(inspect(visitsCountMap, { showHidden: true }));

}, 10000);

/* output

WeakMap { }

const { inspect } = require('util');

let visitsCountMap = new WeakMap(); // Menyimpan daftar user

function countUser(user) {
    let count = visitsCountMap.get(user) || 0;
    visitsCountMap.set(user, count + 1);
}

let jonas = { name: "Jonas" };
countUser(jonas);                // Menambahkan user "Jonas"

jonas = null;                    // Data object "Jonas" dihapus

// delay dibutuhkan untuk menunggu garbage collector bekerja
setTimeout(function() {
  console.log(inspect(visitsCountMap, { showHidden: true }));
}, 10000);

/* output
  WeakMap {  }
*/

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WeakMap

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