Document Object Model (DOM)
The primary purpose of using JavaScript in a web page is to make that page interactive: the JavaScript language is used to program logical decisions that will effect what is shown on the page. It does this primarily by changing the HTML rendered by the browser. For example, JavaScript can be used to change the text inside a <p>, add addition <li> elements to a list, or to give a <div> a new CSS class attribute.
The programmatic representation of the HTML elements currently being shown by the browser is known as the Document Object Model (DOM). In web programming JavaScript code is used to modify the DOM (HTML elements currently being shown by the browser) in response to user input, thereby making the page interactive. This chapter introduces the Document Object Model and how to use JavaScript to manipulate it through user-driven interaction.
In this chapter, we will explore following topics: