Comece Aqui

Table of Content

Table of Content

Table of Content

Objects and Arrays

Objects and Arrays

Objects and arrays are fundamental data structures in JavaScript. Objects store data in key-value pairs, while arrays hold ordered collections of values.

Objects and arrays are fundamental data structures in JavaScript. Objects store data in key-value pairs, while arrays hold ordered collections of values.

Objects in JavaScript

An object is a collection of properties, where each property is a key-value pair.

Creating an Object

An object can be created using curly braces {} with key-value pairs inside.

let person = {
  name: "Alice",
  age: 30,
  isStudent: false
};

Accessing Object Properties

Properties can be accessed using dot notation or bracket notation.

console.log(person.name); // Outputs: Alice
console.log(person["age"]); // Outputs: 30

Modifying Object Properties

Properties can be changed or added dynamically.

person.age = 31; // Modify existing property
person.city = "New York"; // Add new property
  
console.log(person);

Deleting Object Properties

The delete keyword removes a property from an object.

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

Checking Property Existence

The in operator checks if a property exists.

console.log("age" in person); // true
console.log("salary" in person); // false

Iterating Over Objects

Objects can be looped through using for...in.

for (let key in person) {
  console.log(key + ": " + person[key]);
}

Adding and Removing Elements

push(value) adds an element to the end.

pop() removes the last element.

unshift(value) adds an element to the beginning.

shift() removes the first element.

fruits.push("Mango");
fruits.pop();
fruits.unshift("Strawberry");
fruits.shift();
  
console.log(fruits);

Nested Objects and Arrays

Objects can contain arrays, and arrays can contain objects.

let student = {
  name: "Emily",
  grades: [90, 85, 88]
};
  
console.log(student.grades[1]); // Outputs: 85
let employees = [
  { name: "Alice", position: "Developer" },
  { name: "Bob", position: "Designer" }
];
  
console.log(employees[0].name); // Outputs: Alice

Conclusion

Objects and arrays are crucial for managing and structuring data in JavaScript. The next section will focus on ES6+ features, which introduce new syntax and functionalities to improve JavaScript development.