Ext JS是一个创建丰富互联网应用程序的跨浏览器的JavaScrip库。它包含：高效率

				/*
				 * Ext JS Library 3.0 Pre-alpha
				 * Copyright(c) 2006-2008, Ext JS, LLC.
				 * licensing@extjs.com
				 * 
				 * http://extjs.com/license
				 */
				
					Ext.lib.Region = function(t, r, b, l) {
						var me = this;
				        me.top = t;
				        me[1] = t;
				        me.right = r;
				        me.bottom = b;
				        me.left = l;
				        me[0] = l;
				    };
				
				    Ext.lib.Region.prototype = {
				        contains : function(region) {
					        var me = this;
				            return ( region.left >= me.left &&
				                     region.right 				                     region.top >= me.top &&
				                     region.bottom 				
				        },
				
				        getArea : function() {
					        var me = this;
				            return ( (me.bottom - me.top) * (me.right - me.left) );
				        },
				
				        intersect : function(region) {
				            var me = this,
				            	t = Math.max(me.top, region.top),
				            	r = Math.min(me.right, region.right),
				            	b = Math.min(me.bottom, region.bottom),
				            	l = Math.max(me.left, region.left);
				
				            if (b >= t && r >= l) {
				                return new Ext.lib.Region(t, r, b, l);
				            }
				        },
				        
				        union : function(region) {
					        var me = this,
				            	t = Math.min(me.top, region.top),
				            	r = Math.max(me.right, region.right),
				            	b = Math.max(me.bottom, region.bottom),
				            	l = Math.min(me.left, region.left);
				
				            return new Ext.lib.Region(t, r, b, l);
				        },
				
				        constrainTo : function(r) {
					        var me = this;
				            me.top = me.top.constrain(r.top, r.bottom);
				            me.bottom = me.bottom.constrain(r.top, r.bottom);
				            me.left = me.left.constrain(r.left, r.right);
				            me.right = me.right.constrain(r.left, r.right);
				            return me;
				        },
				
				        adjust : function(t, l, b, r) {
					        var me = this;
				            me.top += t;
				            me.left += l;
				            me.right += r;
				            me.bottom += b;
				            return me;
				        }
				    };
				
				    Ext.lib.Region.getRegion = function(el) {
				        var p = Ext.lib.Dom.getXY(el),
				        	t = p[1],
				        	r = p[0] + el.offsetWidth,
				        	b = p[1] + el.offsetHeight,
				        	l = p[0];
				
				        return new Ext.lib.Region(t, r, b, l);
				    };