WHAT IS AN OBJECT?

Objects group together a set of variables and functions to create a modelof a something you would recognize from the real world. In an object,variables and functions take on new names.

Document Object Model

The Document Object Model (DOM) specifies how browsers should create a model of an HTML page and how JavaScript can access and update the contents of a web page while it is in the browser window.

• The browser represents the page using a DOM tree.
• DOM trees have four types of nodes: document nodes, element nodes, attribute nodes, and text nodes.
• You can select element nodes by their id or cl ass attributes, by tag name, or using CSS selector syntax.
• Whenever a DOM query can return more than one node, it will always return a Nadel i st.
• From an element node, you can access and update its content using properties such as textContent and i nnerHTML or using DOM manipulation techniques.
• An element node can contain multiple text nodes and child elements that are siblings of each other.
• In older browsers, implementation of the DOM is inconsistent (and is a popular reason for using jQuery).
• Browsers offer tools for viewing the DOM tree .