AJAX - The Complete Reference

370 Part II: Developing an Ajax Library^

padding: 10px;

border: solid 2px black; }

.draggable {cursor: move;}

.draggable:hover {border: solid 5px yellow;}

</style>

<script type="text/javascript"

src="http://ajaxref.com/ch8/ajaxtcr.js"></script>

<script type="text/javascript">

function getStyle(obj, styleName)

{ /* abstraction to address varying browser methods to calculate a style value */

var style = "";

if (obj.style[styleName])

style = obj.style[styleName];

else if (obj.currentStyle)

style = obj.currentStyle[styleName];

else if (window.getComputedStyle)

{

var computedStyle = window.getComputedStyle(obj, "");

style = computedStyle.getPropertyValue(styleName);

}

return style;

}

function getHighestZIndex()

{ /* find the highest Z-index in the document to put the drug object

higher */

var highestZIndex = 0;

var elements = document.getElementsByTagName("*");

for (var i=0;i<elements.length;i++)

{

var curZIndex = getStyle(elements[i], "zIndex");

if (curZIndex != "")

highestZIndex = Math.max(highestZIndex, parseInt(curZIndex));

}

return highestZIndex;

}

/* addressing the wonderful world of cross-browser event handling */

function fixE(e) { return e || window.event; }

function getPosition(e)

{ /* make sure to compensate for the different position

value calculations in browsers */

var position = {};

if (e.pageX)

{

position.x = e.pageX;

position.y = e.pageY;

}