Object Properties in JavaScript

What Are Object Properties?

• Properties are key-value pairs associated with JavaScript objects.

• Each property has:

  • A key (also called name)

  • A value (can be any data type)

• Properties define the characteristics or data of an object.

Defining Properties

const person = {  name: "Alice",  // key: name, value: "Alice"  age: 30,  isStudent: false};

Accessing Properties

Dot Notation

console.log(person.name);  // Alice

Bracket Notation

console.log(person["age"]); // 30

• Useful when property names are dynamic or not valid identifiers.

Adding or Modifying Properties

person.city = "New York";           // Add new propertyperson["country"] = "USA";           // Another way to addperson.age = 31;                    // Modify existing property

Deleting Properties

delete person.isStudent;console.log(person.isStudent);  // undefined

Property Attributes (Advanced)

Properties have internal attributes:

You can check or define these using:

Object.getOwnPropertyDescriptor(person, "name");Object.defineProperty(person, "name", { writable: false });

Checking if Property Exists

"name" in person;           // trueperson.hasOwnProperty("age"); // true

Summary

Want me to explain property descriptors or show how to iterate properties?