"use strict";
/*
* Object Example in JavaScript
* ----------------------------
* Demonstrates:
* 1. Creating objects
* 2. Accessing properties
* 3. Adding and updating properties
* 4. Iterating over properties
* 5. Using Object utility methods
* 6. Creating reusable functions
*/
/*
Common Object Methods
---------------------
const user = {
id: 1,
name: "Luna"
};
// Returns property names
Object.keys(user);
// Returns property values
Object.values(user);
// Returns key/value pairs
Object.entries(user);
// Creates a shallow copy
Object.assign({}, user);
// Prevent modifications
Object.freeze(user);
// Prevent adding/removing properties
Object.seal(user);
// Checks if property belongs directly to object
Object.hasOwn(user, "name");
*/
// Create an object using an object literal (recommended)
const person = {
firstName: "John",
lastName: "Doe",
age: 35,
isEmployed: true
};
/**
* Returns a formatted description of a person.
*
* @param {Object} personObject - Person object.
* @returns {string} Formatted description.
*/
function getPersonSummary(personObject) {
return `${personObject.firstName} ${personObject.lastName} is ${personObject.age} years old.`;
}
// ------------------------------------------------------------------
// Accessing Object Properties
// ------------------------------------------------------------------
console.log("=== Accessing Properties ===");
console.log(person.firstName); // Dot notation
console.log(person["lastName"]); // Bracket notation
// ------------------------------------------------------------------
// Updating Properties
// ------------------------------------------------------------------
console.log("\n=== Updating Properties ===");
person.age = 31;
console.log(person);
// ------------------------------------------------------------------
// Adding New Properties
// ------------------------------------------------------------------
console.log("\n=== Adding Properties ===");
person.city = "New York";
console.log(person);
// ------------------------------------------------------------------
// Calling a Function with an Object
// ------------------------------------------------------------------
console.log("\n=== Function Example ===");
console.log(getPersonSummary(person));
// ------------------------------------------------------------------
// Checking Property Existence
// ------------------------------------------------------------------
console.log("\n=== Property Checks ===");
console.log("age" in person); // true
console.log("salary" in person); // false
// ------------------------------------------------------------------
// Iterating Through Object Properties
// ------------------------------------------------------------------
console.log("\n=== Iteration ===");
for (const key in person) {
if (Object.hasOwn(person, key)) {
console.log(`${key}: ${person[key]}`);
}
}
// ------------------------------------------------------------------
// Object.keys()
// ------------------------------------------------------------------
console.log("\n=== Object.keys() ===");
const keys = Object.keys(person);
console.log(keys);
// ------------------------------------------------------------------
// Object.values()
// ------------------------------------------------------------------
console.log("\n=== Object.values() ===");
const values = Object.values(person);
console.log(values);
// ------------------------------------------------------------------
// Object.entries()
// ------------------------------------------------------------------
console.log("\n=== Object.entries() ===");
const entries = Object.entries(person);
for (const [key, value] of entries) {
console.log(`${key}: ${value}`);
}
// ------------------------------------------------------------------
// Cloning an Object
// ------------------------------------------------------------------
console.log("\n=== Cloning ===");
// Create a shallow copy
const copiedPerson = {
...person
};
console.log(copiedPerson);
// ------------------------------------------------------------------
// Freezing an Object
// ------------------------------------------------------------------
console.log("\n=== Object.freeze() ===");
const settings = Object.freeze({
theme: "dark",
language: "en"
});
console.log(settings);
// settings.theme = "light"; // Ignored or throws in strict mode
// ------------------------------------------------------------------
// Complete Object Output
// ------------------------------------------------------------------
console.log("\n=== Final Objects ===");
console.log("Person:", person);
console.log("Copy:", copiedPerson);
console.log("Settings:", settings);
/*
run:
=== Accessing Properties ===
John
Doe
=== Updating Properties ===
{ firstName: 'John', lastName: 'Doe', age: 31, isEmployed: true }
=== Adding Properties ===
{
firstName: 'John',
lastName: 'Doe',
age: 31,
isEmployed: true,
city: 'New York'
}
=== Function Example ===
John Doe is 31 years old.
=== Property Checks ===
true
false
=== Iteration ===
firstName: John
lastName: Doe
age: 31
isEmployed: true
city: New York
=== Object.keys() ===
[ 'firstName', 'lastName', 'age', 'isEmployed', 'city' ]
=== Object.values() ===
[ 'John', 'Doe', 31, true, 'New York' ]
=== Object.entries() ===
firstName: John
lastName: Doe
age: 31
isEmployed: true
city: New York
=== Cloning ===
{
firstName: 'John',
lastName: 'Doe',
age: 31,
isEmployed: true,
city: 'New York'
}
=== Object.freeze() ===
{ theme: 'dark', language: 'en' }
=== Final Objects ===
Person: {
firstName: 'John',
lastName: 'Doe',
age: 31,
isEmployed: true,
city: 'New York'
}
Copy: {
firstName: 'John',
lastName: 'Doe',
age: 31,
isEmployed: true,
city: 'New York'
}
Settings: { theme: 'dark', language: 'en' }
*/
