📘 網頁程式設計作業統整

function evaluateScore(score) {
  if (score < 0 || score > 100) {
    return "無效的分數，分數必須介於 0 到 100 之間。";
  }
  let grade = "";
  let comment = "";
  if (score >= 90) {
    grade = "A";
    comment = "表現優異，繼續保持！";
  } else if (score >= 80) {
    grade = "B";
    comment = "良好表現，還有進步空間。";
  } else if (score >= 70) {
    grade = "C";
    comment = "普通，需要多加練習。";
  } else if (score >= 60) {
    grade = "D";
    comment = "勉強及格，請多努力。";
  } else {
    grade = "F";
    comment = "不及格，請重新複習課程內容。";
  }
  return "得分: " + score + ", 等第: " + grade + " (" + comment + ")";
}
console.log(evaluateScore(95));

function getFibonacciSeries(n) {
  if (n <= 0) return [];
  if (n === 1) return [0];
  const series = [0, 1];
  for (let i = 2; i < n; i++) {
    const nextNum = series[i - 1] + series[i - 2];
    series.push(nextNum);
  }
  return series;
}
console.log("前 5 項費氏數列: ", getFibonacciSeries(5));

function calculateSensorAverage(sensorData) {
  const validReadings = [];
  let index = 0;
  while (index < sensorData.length) {
    const currentData = sensorData[index];
    if (currentData === -999) {
      console.log("讀取到結束訊號 -999，停止讀取。");
      break;
    }
    validReadings.push(currentData);
    index++;
  }
  if (validReadings.length === 0) return 0;
  let sum = 0;
  for (let i = 0; i < validReadings.length; i++) {
    sum += validReadings[i];
  }
  const average = sum / validReadings.length;
  console.log("有效讀取次數: " + validReadings.length);
  return average;
}
console.log("平均溫度: " + calculateSensorAverage([25.3, 26.1, 24.8, -999, 28.0]));

const hero = {
  name: "亞瑟",
  level: 1,
  hp: 100,
  maxHp: 100,
  attackPower: 15,
  isAlive: true,
  takeDamage(damage) {
    if (!this.isAlive) {
      console.log(this.name + " 已經陣亡，無法再受到傷害。");
      return;
    }
    this.hp -= damage;
    console.log(this.name + " 受到 " + damage + " 點傷害！目前生命值: " + this.hp + "/" + this.maxHp);
    if (this.hp <= 0) {
      this.hp = 0;
      this.isAlive = false;
      console.log(this.name + " 不幸陣亡了！");
    }
  },
  levelUp() {
    if (!this.isAlive) {
      console.log(this.name + " 已經陣亡，無法升級。");
      return;
    }
    this.level += 1;
    this.maxHp += 20;
    this.hp = this.maxHp;
    this.attackPower += 5;
    console.log(this.name + " 升級了！目前等級: " + this.level + ", 最大生命值: " + this.maxHp);
  }
};
hero.takeDamage(30);
hero.levelUp();

const jsonString = '{"catalogName":"科技圖書館","books":[{"id":"B01","title":"JavaScript 入門","author":"林小明","price":390}]}';
const catalog = JSON.parse(jsonString);
console.log("圖書館名稱: " + catalog.catalogName);
const newBook = { id: "B04", title: "HTML5 網頁美學", author: "王大同", price: 350 };
catalog.books.push(newBook);
console.log("序列化 JSON: ", JSON.stringify(catalog));

const tasks = [
  { name: "準備期末報告", completed: false },
  { name: "繳交作業四", completed: true }
];
function showTasksByStatus(completedStatus) {
  for (let i = 0; i < tasks.length; i++) {
    if (tasks[i].completed === completedStatus) {
      console.log("- " + tasks[i].name);
    }
  }
}
showTasksByStatus(false);

function calculateIncomeTax(annualIncome) {
  if (annualIncome <= 0) return 0;
  let tax = 0;
  if (annualIncome <= 500000) {
    tax = annualIncome * 0.05;
  } else if (annualIncome <= 1200000) {
    tax = 500000 * 0.05 + (annualIncome - 500000) * 0.12;
  } else {
    tax = 500000 * 0.05 + 700000 * 0.12 + (annualIncome - 1200000) * 0.20;
  }
  return tax;
}
console.log("應繳所得稅: " + calculateIncomeTax(800000));

const weatherJson = '{"location":"金門","days":["週一","週二","週三"],"temperatures":[28.5, 31.2, 27.0]}';
const data = JSON.parse(weatherJson);
let maxTemp = data.temperatures[0];
for (let i = 1; i < data.temperatures.length; i++) {
  if (data.temperatures[i] > maxTemp) maxTemp = data.temperatures[i];
}
console.log("最高溫: " + maxTemp);

const studentGrades = [
  { name: "小明", score: 85 },
  { name: "小華", score: 58 }
];
function groupStudents(students) {
  const passed = [];
  const failed = [];
  for (let i = 0; i < students.length; i++) {
    if (students[i].score >= 60) passed.push(students[i].name);
    else failed.push(students[i].name);
  }
  console.log("及格: " + passed.join(", "));
  console.log("不及格: " + failed.join(", "));
}
groupStudents(studentGrades);

const inventorySystem = {
  storeName: "全家便利店 (大學店)",
  items: [
    { name: "御飯糰", price: 35, quantity: 12 },
    { name: "黑咖啡", price: 45, quantity: 20 }
  ],
  calculateTotalValue() {
    let totalValue = 0;
    for (let i = 0; i < this.items.length; i++) {
      totalValue += this.items[i].price * this.items[i].quantity;
    }
    return totalValue;
  },
  restockItem(itemName, qty) {
    for (let i = 0; i < this.items.length; i++) {
      if (this.items[i].name === itemName) {
        this.items[i].quantity += qty;
        console.log(`[補貨] ${itemName} 成功補貨 ${qty} 個！`);
      }
    }
  }
};
console.log("初始總價值: " + inventorySystem.calculateTotalValue());
inventorySystem.restockItem("黑咖啡", 10);
console.log("更新後總價值: " + inventorySystem.calculateTotalValue());

function mathTool(num1, num2, action) {
    return action(num1, num2);
}
console.log(mathTool(10, 5, (a, b) => a + b)); // 輸出: 15
console.log(mathTool(10, 5, (a, b) => a - b)); // 輸出: 5

(function() {
    let count = 100;
    console.log("IIFE 內部的 count: " + count);
})();
// 外部嘗試存取 count 會發生 ReferenceError: count is not defined

const prices = [100, 200, 300, 400];
const discounted = prices.map(p => p * 0.8);
console.log("八折後價格:", discounted);

function cleanData(arr) {
    arr.pop();
    arr.unshift("Start");
}
const dataList = [1, 2, 3];
cleanData(dataList);
console.log("修改後的原始陣列:", dataList);

const multiplier = (factor) => (n) => n * factor;
const double = multiplier(2);
const triple = multiplier(3);
console.log("2 倍計算:", double(10));
console.log("3 倍計算:", triple(10));

function myFilter(arr, callback) {
    const result = [];
    for (let i = 0; i < arr.length; i++) {
        if (callback(arr[i])) {
            result.push(arr[i]);
        }
    }
    return result;
}
console.log(myFilter([1, 2, 3, 4], x => x > 2));

const users = [
    { name: "Alice", age: 25 },
    { name: "Bob", age: 17 },
    { name: "Charlie", age: 20 }
];
const adults = users.filter(user => user.age >= 18);
console.log("成年人列表:", adults);

function process(a, b) {
    a.push(99); // 傳址修改 (會影響外部)
    b = [100];  // 重新賦值 (指向新記憶體位址，不影響外部)
}
let listA = [1, 2];
let listB = [3, 4];
process(listA, listB);
console.log("listA (傳址修改):", listA);
console.log("listB (重新賦值):", listB);

console.log("任務開始...");
setTimeout(() => {
    console.log("延遲 2 秒的非同步任務完成");
}, 2000);
console.log("任務結束，等待非同步中...");

function calculateTotal(cart, discountFunc) {
    const total = cart.reduce((sum, price) => sum + price, 0);
    return discountFunc(total);
}
const cartPrices = [100, 250, 400];
console.log("折後總價:", calculateTotal(cartPrices, t => t - 100));

const config = { port: 8080, dbUrl: "mongodb://localhost" };
console.log("Port (點存取):", config.port);
console.log("DB URL (中括號存取):", config["dbUrl"]);

const req = { body: { username: "yoyo", email: "yoyo@nqu.edu" } };
const { username, email } = req.body;
console.log("解構出的資料:", username, email);

const posts = [{ id: 1, title: "後端架構" }, { id: 2, title: "邊緣計算" }];
posts.forEach(post => {
    console.log(`<li>ID: ${post.id}, Title: ${post.title}</li>`);
});

const params = {};
const key = "userId";
params[key] = "111410517";
console.log("動態參數字典:", params);

function fetchData(id, callback) {
    if (id <= 0) {
        return callback("無效的 ID 參數", null);
    }
    const fakeData = { id: id, status: "OK" };
    callback(null, fakeData); 
}
fetchData(1, (err, data) => {
    if (err) console.error("發生錯誤: " + err);
    else console.log("取得資料成功:", data);
});

function safeParseJSON(jsonStr, callback) {
    try {
        const obj = JSON.parse(jsonStr);
        callback(null, obj);
    } catch (err) {
        callback(err, null);
    }
}
safeParseJSON('{"items":[1,2]}', (err, res) => {
    if (err) console.log("解析失敗");
    else console.log("解析成功，items:", res.items);
});

function fakeGet(sql, params, callback) {
    const fakeRow = { id: 1, title: "後端非同步與錯誤優先" };
    if (params[0] !== 1) {
        return callback(new Error("SQL 錯誤: 找不到該筆資料 (Record Not Found)"), null);
    }
    callback(null, fakeRow);
}
fakeGet("SELECT * FROM posts WHERE id = ?", [2], (err, data) => {
    if (err) console.log("查詢失敗，如預期拋錯：" + err.message);
    else console.log("查詢結果:", data);
});

const userSession = { loggedIn: true, name: "晨祐" };
console.log(`歡迎看板: ${userSession.loggedIn ? `Hello, ${userSession.name}` : "請先登入"}`);

const textList = ["這是一篇非常長長長長長的文章", "短文"];
const processed = textList.map(text => text.length > 10 ? text.slice(0, 10) + "..." : text);
console.log("處理後結果:", processed);

function checkAdmin(role, callback) {
    if (role !== "admin") {
        callback(new Error("Access Denied"), null);
        return;
    }
    callback(null, "Welcome");
}
checkAdmin("user", (err, msg) => {
    if (err) console.log("安全攔截: " + err.message);
    else console.log(msg);
});