looping data yang mempunyai detail

main.js

const { performance } = require("perf_hooks");

// biasanya ini terjadi di website POS dimana
// ada laporan yang harus group sesuai master nya
// lalu keluarin detailnya

// ========= start fill data master + detail ============
const masters = [];
const details = [];

for (let i = 0; i < 5000; i++) {
  masters.push({
    id: i,
    data_master: "blabla",
  });

  for (let j = 0; j < 2; j++) {
    details.push({
      id_master: i,
      data_detail: "blalbalba",
    });
  }
}
// ========= end fill data master + detail ============

// ========= start loop ============
let startTime1 = performance.now();

masters.forEach((m) => {
  // do something
  details.forEach((d) => {
    // data diambil dengan loop jika detail.id_master nya = master.id O(n)
    if (d.id_master === m.id) {
      // do something
    }
  });
});

let endTime1 = performance.now();
let time1 = (endTime1 - startTime1) / 1000;

console.log(`hasil tanpa map ${time1}`);
// ========= end loop ============

let startTime2 = performance.now();
// ========= start pindahin data ke map ============
let newMap = {};
details.forEach((d) => {
  if (!newMap[d.id_master]) {
    newMap[d.id_master] = [];
  }
  newMap[d.id_master].push(d);
  // console.log(newMap[d.id_master]);
});
// ========= end pindahin data ke map ============

// ========= start loop ============
masters.forEach((m) => {
  // do something

  // data diambil dari map yang mempunyai index / nama field id master O(1)
  const det = newMap[m.id];
  det.forEach((d) => {
    // do something
  });
});
// ========= end loop ============

let endTime2 = performance.now();
let time2 = (endTime2 - startTime2) / 1000;
console.log(`hasil dengan map ${time2}`);