document ready vanilla js with code examples

Document Ready with Vanilla JavaScript

In web development, it is essential to ensure that the HTML document has been fully loaded before you manipulate it with JavaScript. You do this to prevent the possibility of accessing elements that have not yet been created, which would result in an error. To ensure that the HTML document is fully loaded, you can use the document ready event in JavaScript.

In this article, we will look at what the document ready event is and how to implement it with Vanilla JavaScript, without relying on any libraries such as jQuery.

What is the Document Ready Event?

The document ready event is fired when the HTML document has finished loading and is ready to be manipulated by JavaScript. This event is fired when all the DOM elements, images, scripts, and styles have been loaded and parsed, but before all the resources such as images have finished loading.

Why Use the Document Ready Event?

The use of the document ready event is crucial in web development because it allows you to ensure that all the elements you want to manipulate with JavaScript are available before you attempt to access them. Without the use of the document ready event, you run the risk of accessing elements that have not yet been created, which can result in errors or unexpected behavior in your application.

Implementing Document Ready with Vanilla JavaScript

Here are two methods to implement the document ready event with Vanilla JavaScript:

Method 1: Using the window.onload Event

The window.onload event is fired when all the resources on the page, including images, scripts, and styles, have been fully loaded. This event can be used to implement the document ready event, as demonstrated in the following code example:

window.onload = function() {
  // Your code here
};

Method 2: Using the DOMContentLoaded Event

The DOMContentLoaded event is fired when the HTML document has been fully loaded and parsed, but before all the resources, such as images, have finished loading. This event can be used to implement the document ready event, as demonstrated in the following code example:

document.addEventListener("DOMContentLoaded", function() {
  // Your code here
});

Conclusion

The document ready event is essential in web development to ensure that the HTML document has been fully loaded before you manipulate it with JavaScript. In this article, we have shown two methods of implementing the document ready event with Vanilla JavaScript, using the window.onload and DOMContentLoaded events.

By using the document ready event, you can ensure that your JavaScript code runs smoothly and without errors, and that all the elements you want to manipulate are available before you attempt to access them.
JavaScript Event Handling

JavaScript event handling is an essential aspect of web development. Events are actions or occurrences that happen in the browser, such as a user clicking a button or a page finishing loading. JavaScript provides a way to handle these events and execute code in response to them.

There are two ways to handle events in JavaScript:

1. Using inline event handlers: Inline event handlers allow you to attach an event handler to an HTML element directly in the HTML code. For example, you can add an onclick attribute to a button element to handle the click event.

<button onclick="alert('Button was clicked!')">Click me</button>

2. Using addEventListener: The addEventListener method allows you to attach an event handler to an element using JavaScript. This method is more flexible and is considered best practice for event handling in JavaScript. For example, you can attach a click event handler to a button element as follows:

const button = document.querySelector('button');
button.addEventListener('click', function() {
  alert('Button was clicked!');
});

There are many different types of events that you can handle in JavaScript, such as mouse events (click, hover), keyboard events (keydown, keyup), and form events (submit, change). You can find a full list of events in the official JavaScript documentation.

Vanilla JavaScript vs. Libraries

Vanilla JavaScript is a term used to describe JavaScript code that does not use any libraries or frameworks. Vanilla JavaScript is the raw JavaScript language and provides all the basic functionality needed to build web applications.

Libraries, such as jQuery, are collections of pre-written JavaScript code that you can use to add additional functionality to your web applications. Libraries are built on top of Vanilla JavaScript and provide a convenient and easy-to-use interface for accessing and manipulating the DOM.

While libraries can make development faster and easier, they can also add additional overhead to your application, both in terms of file size and processing time. Vanilla JavaScript is a good option if you want to keep your codebase small and fast or if you want to have a deeper understanding of how the code works.

However, if you need more advanced functionality or if you're working on a large-scale project, a library may be a better choice. It's important to weigh the benefits and drawbacks of each option and choose the one that best suits your needs.

In conclusion, knowing the basics of Vanilla JavaScript and event handling is crucial for web development, and using libraries can make development easier and faster. Understanding when to use Vanilla JavaScript or a library will help you make the right choice for your project.

Popular questions

1. What is the purpose of using document.addEventListener("DOMContentLoaded", function(){ ... }); in Vanilla JavaScript?

The document.addEventListener("DOMContentLoaded", function(){ ... }); is used to ensure that the DOM (Document Object Model) is fully loaded before executing JavaScript code. This is particularly important when you have JavaScript code that interacts with elements on the page, as the code needs to have access to the elements in the DOM in order to manipulate them.

2. What is the difference between window.onload and document.addEventListener("DOMContentLoaded", function(){ ... }); in Vanilla JavaScript?

The window.onload event fires when all assets, including images and stylesheets, are fully loaded. On the other hand, the document.addEventListener("DOMContentLoaded", function(){ ... }); event fires when the DOM is ready, which is before all assets are loaded. So if you need to access and manipulate elements in the DOM, it is recommended to use document.addEventListener("DOMContentLoaded", function(){ ... }); instead of window.onload.

3. How can you select elements in Vanilla JavaScript?

There are several methods to select elements in Vanilla JavaScript, including:

• document.getElementById: Selects an element with a specific id.
• document.querySelector: Selects the first element that matches a CSS selector.
• document.querySelectorAll: Selects all elements that match a CSS selector.

For example, you can select an element with the id example using document.getElementById("example").

4. How can you add a class to an element in Vanilla JavaScript?

You can add a class to an element in Vanilla JavaScript using the classList property. The classList property is a read-write property that provides access to the classes of an element. You can add a class using the add method, for example:

const element = document.querySelector(".example");
element.classList.add("new-class");

5. How can you manipulate the styles of an element in Vanilla JavaScript?

You can manipulate the styles of an element in Vanilla JavaScript using the style property. The style property provides access to the inline styles of an element, allowing you to set or retrieve the values of CSS properties.

For example, you can set the background color of an element to blue using:

const element = document.querySelector(".example");
element.style.backgroundColor = "blue";

Tag

JavaScript