ajax实例

				/**************************************************
				 * dom-drag.js
				 * 09.25.2001
				 * www.youngpup.net
				 **************************************************
				 * 10.28.2001 - fixed minor bug where events
				 * sometimes fired off the handle, not the root.
				 **************************************************/
				
				var Drag = {
				
					obj : null,
				
					init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
					{
						o.onmousedown	= Drag.start;
				
						o.hmode			= bSwapHorzRef ? false : true ;
						o.vmode			= bSwapVertRef ? false : true ;
				
						o.root = oRoot && oRoot != null ? oRoot : o ;
				
						if (o.hmode  && isNaN(parseInt(o.root.style.left  ))) o.root.style.left   = "0px";
						if (o.vmode  && isNaN(parseInt(o.root.style.top   ))) o.root.style.top    = "0px";
						if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right  = "0px";
						if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";
				
						o.minX	= typeof minX != 'undefined' ? minX : null;
						o.minY	= typeof minY != 'undefined' ? minY : null;
						o.maxX	= typeof maxX != 'undefined' ? maxX : null;
						o.maxY	= typeof maxY != 'undefined' ? maxY : null;
				
						o.xMapper = fXMapper ? fXMapper : null;
						o.yMapper = fYMapper ? fYMapper : null;
				
						o.root.onDragStart	= new Function();
						o.root.onDragEnd	= new Function();
						o.root.onDrag		= new Function();
					},
				
					start : function(e)
					{
						var o = Drag.obj = this;
						e = Drag.fixE(e);
						var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
						var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
						o.root.onDragStart(x, y);
				
						o.lastMouseX	= e.clientX;
						o.lastMouseY	= e.clientY;
				
						if (o.hmode) {
							if (o.minX != null)	o.minMouseX	= e.clientX - x + o.minX;
							if (o.maxX != null)	o.maxMouseX	= o.minMouseX + o.maxX - o.minX;
						} else {
							if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
							if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
						}
				
						if (o.vmode) {
							if (o.minY != null)	o.minMouseY	= e.clientY - y + o.minY;
							if (o.maxY != null)	o.maxMouseY	= o.minMouseY + o.maxY - o.minY;
						} else {
							if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
							if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
						}
				
						document.onmousemove	= Drag.drag;
						document.onmouseup		= Drag.end;
				
						return false;
					},
				
					drag : function(e)
					{
						e = Drag.fixE(e);
						var o = Drag.obj;
				
						var ey	= e.clientY;
						var ex	= e.clientX;
						var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
						var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
						var nx, ny;
				
						if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
						if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
						if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
						if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);
				
						nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
						ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));
				
						if (o.xMapper)		nx = o.xMapper(y)
						else if (o.yMapper)	ny = o.yMapper(x)
				
						Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
						Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
						Drag.obj.lastMouseX	= ex;
						Drag.obj.lastMouseY	= ey;
				
						Drag.obj.root.onDrag(nx, ny);
						return false;
					},
				
					end : function()
					{
						document.onmousemove = null;
						document.onmouseup   = null;
						Drag.obj.root.onDragEnd(	parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]), 
													parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));
						Drag.obj = null;
					},
				
					fixE : function(e)
					{
						if (typeof e == 'undefined') e = window.event;
						if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
						if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
						return e;
					}
				};