Hover ad

From Wikipedia, the free encyclopedia

Hover ads are a special type of pop-up ads created using Dynamic HTML, JavaScript and similar web browser technologies. Because they do not scroll with the web-page, they appear to "hover" over the page, usually obscuring the content.

1 Background
2 Technology
3 References
4 External links

[edit] Background

Being among the most effective forms of web advertising, pop-up ads acquired a certain share of online advertising solutions and technologies. The first Internet popups were created using the window.open() JavaScript function, which opens a new browser window. The advertising content was presented in the window as HTML content loaded from a web address. These popups were easily blocked by popup blockers, such as the Google Toolbar, which could be downloaded at no cost.

In order to circumvent these popup blockers, some online advertisers tried a different method of opening pop-ups, Dynamic HTML, which is more integral to the functioning of a web-browser and thus harder to block.

[edit] Technology

Hover ads are developed around several web browser technologies but in the centre of their realisation is utilised DHTML, a technique where JavaScript modifies the content of the page. Using JavaScript, certain levels and objects of the browser’s DOM are manipulated to produce window-like visual DHTML elements representing hover ads or hover ad windows. The basic attribute used is a CSS HTML element attribute - position. Modern browsers implement cascading style sheets in order to separate presentation from content. The CSS technology also enables the JavaScript content of a web page to manipulate programmatically CSS attributes of various HTML elements constituting the web page's content. The first movable HTML elements were introduced in Netscape 4 with the so called layer technology. Now it has been deprecated. Hover ads tend to be very hard to block by popup blocking software because the hover ad window is an integral part of the HTML content of the web page. Thus a software filtering the content has no algorithmical means of recognizing and removing parts of the content, either descriptive or procedural, that create, populate and manipulate the hover ad's window.