const tags = ["js", "react", "js", "ts", "react", "node"];

const uniqueTags = [...new Set(tags)];

console.log(uniqueTags); // ["js", "react", "ts", "node"]

function markVisitedPages(paths) {
  const visited = new Set();

  for (const path of paths) {
    if (visited.has(path)) {
      console.log("เคยเข้าแล้ว:", path);
      continue;
    }

    visited.add(path);
    console.log("เข้าใหม่:", path);
  }

  return visited;
}

markVisitedPages(["/", "/docs", "/", "/pricing", "/docs"]);

function countFrequency(values) {
  const freq = new Map();

  for (const value of values) {
    const current = freq.get(value) ?? 0;
    freq.set(value, current + 1);
  }

  return freq;
}

const result = countFrequency(["A", "B", "A", "C", "B", "A"]);
console.log(result.get("A")); // 3
console.log(result.get("C")); // 1

const productNameByCode = new Map([
  ["P-100", "Mechanical Keyboard"],
  ["P-200", "Wireless Mouse"],
  ["P-300", "USB-C Hub"],
]);

function getProductName(code) {
  return productNameByCode.get(code) ?? "ไม่พบสินค้า";
}

console.log(getProductName("P-200")); // "Wireless Mouse"

const profileCache = new Map();

async function getUserProfile(userId) {
  if (profileCache.has(userId)) {
    return profileCache.get(userId);
  }

  const profile = await fakeApiFetch(userId);
  profileCache.set(userId, profile);
  return profile;
}

async function fakeApiFetch(userId) {
  return { id: userId, name: "User-" + String(userId) };
}

const seen = new Set();

seen.add("A");
seen.add("B");
seen.add("A"); // ค่าซ้ำจะไม่ถูกเพิ่ม

console.log(seen.has("B")); // true
console.log(seen.has("C")); // false

seen.delete("A");
console.log([...seen]); // ["B"]

const userById = new Map();

userById.set(101, "Alice");
userById.set(102, "Bob");
userById.set(101, "Alice Cooper"); // key เดิม = อัปเดตค่า

console.log(userById.get(101)); // "Alice Cooper"
console.log(userById.has(999)); // false

userById.delete(102);
console.log([...userById.entries()]); // [[101, "Alice Cooper"]]