Javascript Objects

JavaScript Objects

Objects in JavaScript are collections of properties and methods. Properties are values associated with the object, while methods are functions defined within the object.

Creating an Object

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

JavaScript Object Properties

Properties are the data points associated with an object, and they are accessible using dot or bracket notation.

Accessing Properties

console.log(person.firstName); // Output: Alice

console.log(person[“age”]); // Output: 25

Adding New Properties

You can add properties dynamically to an existing object.

person.country = “USA”;

console.log(person.country); // Output: USA

JavaScript Object Methods

Methods are functions within an object that allow for interaction with the object’s properties.

Example of Object Method

let car = { brand: “Toyota”, model: “Camry”, start: function() { return “The car has started.”; } }; console.log(car.start()); // Output: The car has started.

JavaScript Object Display

To display objects and their properties, you can use several methods:

Using console.log() for complete object output:

console.log(person);

Using for…in loop to loop through all properties:

for (let prop in person) {

console.log(prop + “: ” + person[prop]);

}

Using Object.values() to get an array of all values in an object:

console.log(Object.values(person)); // Output: [“Alice”, “Doe”, 25,

“USA”]

JavaScript Object Constructors

Constructors allow you to create multiple instances of an object with similar properties and methods. By convention, constructor functions use uppercase for their names.

Example of Constructor Function

function Person(firstName, lastName, age) { this.firstName = firstName; this.lastName = lastName; this.age = age; } let person1 = new Person(“John”, “Smith”, 30); let person2 = new Person(“Jane”, “Doe”, 28); console.log(person1.firstName); // Output: John console.log(person2.age); // Output: 28

Benefits of Constructors

Constructors allow code reuse and consistency across multiple objects. Additionally, you can use the prototype property to add methods that will be shared among all instances:

Person.prototype.greet = function() { return `Hello, ${this.firstName} ${this.lastName}!`; }; console.log(person1.greet()); // Output: Hello, John Smith!

Request more information

Javascript Objects