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JavaScript Web development

JavaScript HTML DOM/Methods

With the HTML DOM, JavaScript can access and change all the elements of an HTML document.

When a web page is loaded, the browser creates a Document Object Model of the page.

The HTML DOM model is constructed as a tree of Objects:

JavaScript HTML DOM
Document Object Model

With the object model, JavaScript gets all the power it needs to create dynamic HTML:

  1. JavaScript can change all the HTML elements in the page
  2. JavaScript can change all the HTML attributes in the page
  3. JavaScript can change all the CSS styles in the page
  4. JavaScript can remove existing HTML elements and attributes
  5. JavaScript can add new HTML elements and attributes
  6. JavaScript can react to all existing HTML events in the page
  7. JavaScript can create new HTML events in the page

What is the DOM?

The DOM is a W3C (World Wide Web Consortium) standard.

The DOM defines a standard for accessing documents:

“The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document.”

The W3C DOM standard is separated into 3 different parts:

  1. Core DOM – standard model for all document types
  2. XML DOM – standard model for XML documents
  3. HTML DOM – standard model for HTML documents

What is the HTML DOM?

The HTML DOM is a standard object model and programming interface for HTML. It defines:

  1. The HTML elements as objects
  2. The properties of all HTML elements
  3. The methods to access all HTML elements
  4. The events for all HTML elements

In other words: The HTML DOM is a standard for how to get, change, add, or delete HTML elements.

JavaScript – HTML DOM Methods

HTML DOM methods are actions you can perform (on HTML Elements). HTML DOM properties are values (of HTML Elements) that you can set or change.

The DOM Programming Interface

The HTML DOM can be accessed with JavaScript (and with other programming languages).

In the DOM, all HTML elements are defined as objects.

The programming interface is the properties and methods of each object.

property is a value that you can get or set (like changing the content of an HTML element).

method is an action you can do (like add or deleting an HTML element).

Example:

The following example changes the content (the innerHTML ) of the <p> element with id=”demo“:

<!DOCTYPE html>
<html>
<body>

<h2>My First Page</h2>

<p id="demo"></p>

<script>
document.getElementById("demo").innerHTML = "Hello World!";
</script>

</body>
</html>

Output:

The innerHTML property can be used to get or change any HTML element, including <html> and <body>.

Enjoy coding!

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