JavaScript Objects

// CREATE
const employee = {
  id: "EMP-001",
  name: "Asha Sharma",
  department: "Engineering",
  salary: 85000,
  skills: ["JavaScript", "React", "Node.js"],
  address: {
    city: "Jaipur",
    state: "Rajasthan"
  }
};

// READ
console.log("Name:", employee.name);
console.log("City:", employee.address.city);
console.log("First skill:", employee.skills[0]);

// UPDATE
employee.salary = 95000;
employee.skills.push("TypeScript");
employee.address.city = "Mumbai";

// ADD new property
employee.joiningDate = "2023-01-15";

// DELETE
delete employee.address;

console.log("\nAfter updates:");
console.log("Salary:", employee.salary);
console.log("Skills:", employee.skills);
console.log("Joining:", employee.joiningDate);
console.log("Address:", employee.address); // undefined

const user = {
  id: 101,
  firstName: "Asha",
  lastName: "Sharma",
  email: "asha@example.com",
  role: "admin",
  preferences: {
    theme: "dark",
    language: "hi"
  }
};

// Basic destructuring
const { firstName, email, role } = user;
console.log(firstName, email, role);

// Rename while destructuring
const { firstName: name, role: userRole } = user;
console.log(name, userRole);

// Default values
const { phone = "Not provided", role: userType = "guest" } = user;
console.log(phone, userType);

// Nested destructuring
const { preferences: { theme, language } } = user;
console.log(theme, language);

// In function parameters (very common in React!)
function displayUser({ firstName, role, email }) {
  console.log(`${firstName} (${role}) — ${email}`);
}
displayUser(user);

const defaults = {
  theme: "light",
  language: "en",
  notifications: true,
  pageSize: 10
};

const userPrefs = {
  theme: "dark",
  language: "hi"
};

// Merge: spread — later properties override earlier ones
const settings = { ...defaults, ...userPrefs };
console.log("Merged settings:", settings);

// Create modified copy (immutable update pattern)
const updatedUser = {
  name: "Asha",
  email: "asha@example.com",
  role: "viewer"
};

const promoted = { ...updatedUser, role: "admin", updatedAt: "2026-06-01" };
console.log("Original role:", updatedUser.role);  // viewer
console.log("New role:", promoted.role);           // admin

// Combining spread with computed keys
const fieldName = "email";
const dynamicUpdate = { ...updatedUser, [fieldName]: "newemail@example.com" };
console.log("Updated email:", dynamicUpdate.email);

// Simulating an API response
const apiResponse = {
  status: "success",
  timestamp: "2026-06-01T10:30:00Z",
  data: {
    user: {
      id: 42,
      name: "Asha Sharma",
      avatar: "/images/asha.jpg",
      stats: {
        orders: 15,
        spent: 125000,
        lastOrder: "2026-05-20"
      }
    }
  },
  meta: {
    page: 1,
    total: 1,
    perPage: 10
  }
};

// Extract needed data
const { data: { user }, meta } = apiResponse;
const { name, stats: { orders, spent } } = user;

console.log("Welcome back,", name);
console.log("Orders:", orders);
console.log("Total spent: ₹" + spent.toLocaleString("en-IN"));

// Object.keys, values, entries for iteration
const statsObj = user.stats;
console.log("\nUser Stats:");
Object.entries(statsObj).forEach(([key, value]) => {
  console.log(" ", key + ":", value);
});