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Drag and Drop

One of the biggest improvements in computer usability was the proliferation of drag-and-drop

behavior, allowing users to drag something from one spot on the screen and drop it somewhere

else to either create an action or simply move the item. This paradigm, developed by XEROX, was

first incorporated into consumer technology in Mac OS 1.0 and since that time has been incorpo-

rated in most personal computer operating systems (including Windows). When Dynamic HTML

was first introduced, developers around the world starting experimenting with drag-and-drop

functionality using JavaScript.

Drag and drop

is a buzzword in usability, so adding this functionality to your Web site or Web

application can win major points with customers and clients. At present time, you can accomplish

drag and drop in two ways using JavaScript: system drag and drop and simulated drag and drop.

System Drag and Drop

System drag and drop is what you probably do on a daily basis when using your Windows,

Macintosh, or other graphical operation system: You drag something from one area of the screen

and drop it somewhere else. To delete a file, you drag it to the trash (Macintosh) or the recycle bin

(Windows); to move a file from one folder to another, you just drag the file from where it is and

drop it into its new home. System drag and drop works because it has help from the operating sys-

tem to complete its task. Currently, only one Web browser on one platform supports system drag

and drop in Web pages, and that is Internet Explorer on Windows (although Mozilla supports it in

XUL-based pages).

A system drag and drop can move in between windows and frames because the drag action is

handled by the operating system. You can drag an image from a Web browser onto your desktop

or into another browser. When you drag it onto your desktop, you download the image; when you

drag it into another browser, the browser displays the image. The communication between the

browser and the desktop (or other browser) is handled by the operating system.

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