Objects¶
Objects are key-value pairs used to store structured data. Each key is a property, and its value can be any data type.
1. Object Creation¶
a) Object Literal¶
const user = {
name: "John",
age: 30,
isAdmin: true
};
b) Using new Object()¶
const user = new Object();
user.name = "John";
user.age = 30;
2. Accessing Properties¶
a) Dot Notation¶
console.log(user.name); // "John"
b) Bracket Notation¶
console.log(user["age"]); // 30
Use brackets when:
- The key has spaces or special characters
- Accessing dynamically
let key = "isAdmin";
console.log(user[key]); // true
3. Modifying Properties¶
user.name = "Mike";
user["age"] = 25;
4. Adding Properties¶
user.email = "test@example.com";
5. Deleting Properties¶
delete user.isAdmin;
6. Nested Objects¶
const product = {
name: "Phone",
specs: {
ram: "8GB",
storage: "128GB"
}
};
console.log(product.specs.ram); // "8GB"
7. Methods (Functions inside objects)¶
const person = {
firstName: "Jane",
greet() {
console.log("Hello!");
}
};
person.greet(); // "Hello!"
8. Looping through Objects¶
for...in loop¶
for (let key in user) {
console.log(key, user[key]);
}
9. Built-in Object Methods¶
Object.keys(user); // ["name", "age"]
Object.values(user); // ["John", 30]
Object.entries(user); // [["name", "John"], ["age", 30]]