HCL Domino Leap Tutorial

Appearance

JavaScript Objects ​

JavaScript objects are a fundamental part of the language, allowing you to store collections of data and more complex entities. In this tutorial, we'll start with the basics and gradually delve into more detailed aspects of JavaScript objects.

What is a JavaScript Object? ​

In JavaScript, an object is a standalone entity, with properties and type. Think of it as a container for values in a key:value format. The keys (or names) act as identifiers for the values stored within the object.

Creating an Object ​

There are several ways to create objects in JavaScript:

Object Literals ​

The simplest way to create an object is using the object literal syntax. This is just a comma-separated list of key: value pairs within curly braces {}.

javascript
const person = {
    firstName: "John",
    lastName: "Doe",
    age: 30
};

The new Keyword ​

You can also create an object using the new keyword followed by Object(). This method is less common for direct object creation.

javascript
const person = new Object();
person.firstName = "John";
person.lastName = "Doe";
person.age = 30;

Accessing Object Properties ​

You can access the properties of an object in two ways:

Dot Notation ​

javascript
console.log(person.firstName); // Output: John

Bracket Notation ​

javascript
console.log(person["lastName"]); // Output: Doe

Bracket notation is especially useful when accessing properties with names that are not valid JavaScript identifiers or when property names are dynamic.

Modifying Object Properties ​

You can modify the properties of an object using the same dot or bracket notation.

javascript
person.age = 31;
console.log(person.age); // Output: 31

Adding New Properties ​

You can add new properties to an object simply by assigning a value to a new property name.

javascript
person.email = "john.doe@example.com";
console.log(person.email); // Output: john.doe@example.com

Deleting Properties ​

You can remove properties from an object using the delete keyword.

javascript
delete person.age;
console.log(person.age); // Output: undefined

Looping Through Object Properties ​

You can loop through the properties of an object using a for...in loop.

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

Methods in Objects ​

Objects can also contain functions, known as methods. Methods are actions that can be performed on objects.

javascript
const person = {
    firstName: "John",
    lastName: "Doe",
    fullName: function () {
        return this.firstName + " " + this.lastName;
    }
};

console.log(person.fullName()); // Output: John Doe

Conclusion ​

JavaScript objects are versatile and powerful, enabling you to group related data and functionality. They play a crucial role in building more complex and maintainable code. Experiment with creating and manipulating objects to get comfortable with these concepts. As you progress, you'll learn more about object-oriented programming in JavaScript, including prototypes and classes, which further leverage the power of objects.