Skip to content

01-Intro-to-objects.md

Latest commit

 

History

History
70 lines (45 loc) · 3.28 KB

01-Intro-to-objects.md

File metadata and controls

70 lines (45 loc) · 3.28 KB

Intro to Objects

What are Objects

In JavaScript, an object is a collection of key-value pairs, where each key is a string (or a symbol) that uniquely identifies a value. This key-value structure enables you to represent real-world entities or concepts in your code. For example, you could create an object to represent a person with properties like name, age, and email.

Creating Objects

There are several ways to create objects in JavaScript. The most common method is by using object literal notation, which involves defining an object directly in your code using curly braces.

let person = {
  name: "Ben Tennyson",
  age: 21,
  email: "ben@example.com",
};

In the above example, we create an object called person with three properties: name, age, and email. The colon separates the key (property name) from its corresponding value.

The keys in this object (name, age, and email) are indeed strings, although they are not enclosed in quotes. In JavaScript object literals, when keys are unquoted and follow the rules for valid JavaScript identifiers (no spaces, start with a letter, etc.), they are treated as strings.

So, even though the keys are not explicitly defined as strings with quotes, they are still interpreted as string keys by default. It's a shorthand syntax that JavaScript provides for convenience.

Accessing Object Properties

Once you have an object, you can access its properties using dot notation or square brackets. Dot notation is the most common and straightforward way to access object properties.

console.log(person.name); // Output: Ben Tennyson
console.log(person.age); // Output: 21
console.log(person.email); // Output: ben@example.com

Learn more about Dot VS Bracket notation here.

Modifying Object Properties

Objects in JavaScript are mutable, meaning you can modify their properties after they are created. To change the value of a property, simply assign a new value to it using the assignment operator (=).

person.age = 19;
console.log(person.age); // Output: 19

In the above example, we modify the age property of the person object and then log the updated value to the console.

Adding and Removing Object Properties

You can also add new properties to an object or remove existing ones dynamically. To add a new property, simply assign a value to a non-existent property.

person.city = "New York";
console.log(person.city); // Output: New York

In this case, we add a city property to the person object and log its value to the console.

To remove a property from an object, you can use the delete keyword followed by the objectname and the property you want to delete.

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

Here, we remove the email property from the person object. Accessing the property afterwards returns undefined, indicating that the property no longer exists.

Conclusion

Objects are an essential part of JavaScript, allowing you to organize and manipulate data in a structured manner. By understanding the basics of objects, you can create more complex programs and handle real-world scenarios effectively. Remember to practice creating, accessing, modifying, and removing properties from objects to solidify your understanding.