JavaScript, DOM, and CSS

CSS (Cascading Style Sheets) is certainly a familiar term for you. CSS allows setting formatting options in a centralized document that is referenced from HTML files. If the job is done right, and CSS is used consistently in a website, CSS will allow you to make visual changes to the entire site (or parts of the site) with very little effort, just by editing the CSS file. There are many books and tutorials on CSS, including the free ones you can find at http://www.w3.org/Style/CSS/ and http://www.w3schools.com/css/default.asp. Although the article that invented the name AJAX (http://www.adaptivepath.com/publications/essays/archives/000385.php) mentions CSS as one of the AJAX ingredients, technically CSS is not required to build successful dynamic web applications. However, its usage is highly recommended because of the significant benefits it brings.

We will do a simple exercise to demonstrate using CSS, and manipulating HTML elements’ styles using the DOM. These...