Working with JavaScript Objects

1. Introduction

In this tutorial, we aim to provide a comprehensive guide to understanding JavaScript objects. We will learn how to create, access, and manipulate objects in JavaScript.

By the end of this tutorial, you should be able to:
- Understand what JavaScript objects are
- Create your own objects
- Access and modify properties of an object
- Use methods with objects

Prerequisites: Basic understanding of JavaScript syntax and data types.

2. Step-by-Step Guide

Understanding JavaScript Objects

JavaScript objects are containers for named values, called properties and methods. The properties of an object define the characteristics of the object, and the methods define the actions the object can perform.

Creating a JavaScript Object

You can define (and create) a JavaScript object with an object literal:

let person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"};

In the example above, 'person' is an object. The object has four properties: firstName, lastName, age and eyeColor.

Accessing Object Properties

You can access object properties in two ways:

1. ObjectName.PropertyName
2. ObjectName["PropertyName"]

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

Changing Object Properties

You can change the value of an object property using the assignment operator:

person.firstName = "Jane"; // changes the firstName property to "Jane"

JavaScript Object Methods

Methods are actions that can be performed on objects. Methods are stored in properties as function definitions.

let person = {
  firstName: "John",
  lastName : "Doe",
  id       : 5566,
  fullName : function() {
    return this.firstName + " " + this.lastName;
  }
};

In the example above, fullName is a method, and it will return "John Doe" when called: person.fullName().

3. Code Examples

Creating a JavaScript Object

let car = {
  make: "Toyota",
  model: "Corolla",
  year: 2020,
  color: "red"
};

console.log(car); // Output: { make: 'Toyota', model: 'Corolla', year: 2020, color: 'red' }

Accessing and Modifying Object Properties

console.log(car.make); // Output: "Toyota"
console.log(car["model"]); // Output: "Corolla"

car.year = 2021; // changes the year property to 2021
console.log(car.year); // Output: 2021

Using Object Methods

let person = {
  firstName: "John",
  lastName : "Doe",
  id       : 5566,
  fullName : function() {
    return this.firstName + " " + this.lastName;
  }
};

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

4. Summary

In this tutorial, we've learned what JavaScript objects are, how to create them, and how to access and modify their properties. We've also learned how to use methods with objects.

The next step in your learning journey could be learning about JavaScript Object Prototypes, or perhaps exploring more about functions and how they work with objects.

Additional resources:
1. Mozilla Developer Network - JavaScript objects
2. W3Schools - JavaScript Objects

5. Practice Exercises

1. Create a JavaScript object representing a book with properties like title, author, year of publication, and a method that returns a summary of the book.
2. Modify the properties of the book object you created, and then print the updated properties.
3. Add a new method to the book object that returns the age of the book based on the current year.

Solutions with explanations and tips for further practice can be found in the additional resources provided.