Skip to content

Properties

Properties

Introduction

Object properties are the key-value pairs stored in an object. Keys are strings (or Symbols), and values can be any type.

Accessing Properties

const user = { name: 'Alice', age: 25 };

// Dot notation
user.name;  // 'Alice'

// Bracket notation (for dynamic keys)
user['name']; // 'Alice'
const key = 'age';
user[key];    // 25

Adding and Updating

const user = { name: 'Alice' };
user.age = 25;           // Add new property
user.name = 'Bob';       // Update existing
user['isActive'] = true; // Bracket notation

Deleting Properties

const user = { name: 'Alice', age: 25 };
delete user.age;
console.log(user.age); // undefined

Property Enumeration

const user = { name: 'Alice', age: 25 };

Object.keys(user);     // ['name', 'age']
Object.values(user);   // ['Alice', 25]
Object.entries(user);  // [['name', 'Alice'], ['age', 25]]

Summary

Access with . (static) or [] (dynamic)
Add/update by assignment
Delete with delete operator
Use Object.keys/values/entries for enumeration

Further Reading

MDN: Working with Objects