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L Layer.clip.height (Property) Layer.clip.height (Property) The height of a layer’s clip region. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: Number primitive myLayer.clip.height N myRect.height N The clip region is defined by an extent rectangle that surrounds the space occupied by it on the screen. An extent rectangle is that smallest rectangle that completely encloses the item. This property specifies the height of that extent rectangle. Warnings: . No longer supported in Netscape 6.0. See also: Clip.height, Rect.height Layer.clip.left (Property) The left edge of a layer’s clip region. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N myRect.left This defines the left edge of the clip region. You could modify this in a loop to create a horizontal wipe transition effect. Warnings: .No longer supported in Netscape 6.0. Number primitive myLayer.clip.left N See also: Clip.left, Rect.left 1297

JavaScript Programmer’s Reference . clip.right . clip.top . clip.width If you are developing scripts that only run in MSIE, there is a rather nice collection of filters that can provide these transitions very elegantly. It s a pity they aren’t available in other browsers. But then layers and clip rectangles aren’t supported in the same way in MSIE so at least there seems to be some alternative approach to creating visual effects on each platform. Warnings: . No longer supported in Netscape 6.0. See also: Clip object, Rect object Layer.clip.bottom (Property) The bottom edge of a layer’s clip region. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N myRect.bottom This defines the bottom edge of the clip region. You could modify this in a loop to create a vertical downwards wipe transition effect. Warnings: .No longer supported in Netscape 6.0. Number primitive myLayer.clip.bottom N See also: Clip.bottom, Rect.bottom 1296

L Layer.clip (Property) A limitation of this technique is that ultimately, only 32 different kinds of events can be combined in this way and this may limit the number of events the browser can support. Since this is only supported by Netscape, the functionality is likely to be deprecated when the standards bodies agree on a standard way of handling events. Then we simply need to wait for the browser manufacturers to support the standardized behavior. In the meantime, we shall have to implement scripts using this capability if we need to build complex event handling systems. A different script will be required for MSIE. You may be able to factor your event handler so that you only have to make platform specific event dispatchers and can call common handling routines that can be shared between MSIE and Netscape. Warnings: . Since a bit mask is being used, this must be an int32 value. This suggests that there can only be 32 different Event types supported by this event propagation model. . This capability is deprecated and is not supported in Netscape 6.0. It never was supported by MSIE which implements a completely different event model. As it turns out, the DOM level 2 event model converges on the MSIE technique. See also: captureEvents(), Document.captureEvents(), Document.releaseEvents(), Element.onevent, Event propagation, Event type constants, Frame object, Layer.releaseEvents(), onMouseMove, Window object, Window.captureEvents(), Window.releaseEvents() Layer.clip (Property) An object that represents the clip region within a layer. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N Rect object myLayer.clip This object represents a clipping rectangle that the visible part of a display object is viewed through. This is most likely used with a layer object. The layer contents would be drawn off-screen and then that part which falls within the clipping rectangle would be displayed in the window. This can be useful for performing wipes and making parts of a layer progressively visible within some kind of transition loop. This object exposes the following properties for accessing Layer clip rectangles: . clip.bottom . clip.height . clip.left 1295

JavaScript Programmer’s Reference Layer.bgColor (Property) The background color of a layer. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N String primitive myLayer.bgColor The background can be colored independently of whether an image is loaded into the background of an object. In fact it may be advisable to set the background color to something similar to the average color of the background image in case the image takes a long time to load or the browser is unable to display a background image.The color can be set using a Hexadecimal triplet, or a plain language color value. The default is a transparent background. Warnings: . No longer supported in Netscape 6.0. See also: Color names, Color value Layer.captureEvents() (Function) Part of the Netscape 4 event propagation complex. Availability: JavaScript 1.2 Netscape 4.0 Deprecated Property/method value type: JavaScript syntax: undefined N myLayer.captureEvents(anEventMask) anEventMask A mask constructed with the manifest event Argument list: constants This is part of the event management suite which allow events to be routed to handlers other than just the one that defaults to being associated with an event. The events to be captured are signified by setting bits in a mask. This method allows you to specify what events are to be routed to the receiving Layer object. The events are specified by using the bitwise OR operator (|) to combine the required event mask constants into a mask that defines the events you want to capture. Refer to the Event Type Constants topic for a list of the event mask values. 1294

L Layer.background (Property) Layer.background (Property) The background object of a layer. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N If a background image is available, then its URL is contained in the src property of the object. Changing the Layer.background.src property value will replace the background with a new one. However, there may be a perceptible delay while the new image is fetched from the web server. Warnings: .No longer supported in Netscape 6.0. Background object myLayer.background See also: Background object Layer.below (Property) The layer immediately below the receiving layer object. JavaScript 1.2 Netscape 4.0 Deprecated Availability: Property/method value type: JavaScript syntax: N Layer object myLayer.below The layers area arranged into a hierarchy and presented to the user as a stack viewed from one end. Given that you are referencing any particular layer, if there is one below it in the stack, this property will yield an object that encapsulates it. Warnings: . There are various intermediate layers created by the browser that may be placed into the layer hierarchy without you having put tags into the document. . No longer supported in Netscape 6.0. Property attributes: ReadOnly. 1293

JavaScript Programmer’s Reference Event name JavaScript JScript N IE Opera Notes onBlur 1.2 + 4.0 + Warning onFocus 1.2 + 4.0 + Warning onLoad 1.2 + 4.0 + Warning onMouseOut 1.2 + 4.0 + Warning onMouseOver 1.2 + 4.0 + Warning onMouseUp 1.2 + 4.0 + Warning Layer() (Constructor) A means of creating new layers in Netscape. Availability: JavaScript 1.2 Netscape 4.0 Deprecated JavaScript syntax: N new Layer() This constructor function should be used with the new operator to instantiate a new layer when needed. This provides a way to create new layers without needing to describe them in the HTML document source. Warnings: . No longer supported in Netscape 6.0. Layer.above (Property) The layer immediately above the receiving layer object, (or null, if this is the highest layer). Availability: JavaScript 1.2 Netscape 4.0 Deprecated Property/method value type: Layer object JavaScript syntax: N myLayer.above Warnings: . No longer supported in Netscape 6.0. Property attributes: ReadOnly. 1292

L Layer object (Object/Navigator) See also: DIV object, Layer.siblingAbove, Layer.siblingBelow, LayerArray object, style object (2) Property JavaScript JScript N IE Opera Notes above 1.2 + 4.0 + Warning, ReadOnly, Deprecated background 1.2 + 4.0 + Warning, Deprecated below 1.2 + 4.0 + Warning, ReadOnly, Deprecated bgColor 1.2 + 4.0 + Warning, Deprecated clip 1.2 + 4.0 + Warning, Deprecated document 1.2 + 4.0 + Warning, ReadOnly, Deprecated hidden 1.2 + 4.0 + Warning, Deprecated left 1.2 + 4.0 + Warning, Deprecated name 1.2 + 4.0 + Warning, ReadOnly, Deprecated pageX 1.2 + 4.0 + Warning, Deprecated pageY 1.2 + 4.0 + Warning, Deprecated parentLayer 1.2 + 4.0 + Warning, ReadOnly, Deprecated siblingAbove 1.2 + 4.0 + Warning, ReadOnly, Deprecated siblingBelow 1.2 + 4.0 + Warning, ReadOnly, Deprecated src 1.2 + 4.0 + Warning, Deprecated top 1.2 + 4.0 + Warning, Deprecated visibility 1.2 + 4.0 + Warning, Deprecated window 1.2 + 4.0 + Warning, Deprecated x 1.2 + 4.0 + Warning, Deprecated y 1.2 + 4.0 + Warning, Deprecated zIndex 1.2 + 4.0 + Warning, Deprecated Method JavaScript JScript N IE Opera Notes load() 1.2 + 4.0 + Warning, Deprecated moveAbove() 1.2 + 4.0 + Warning, Deprecated moveBelow() 1.2 + 4.0 + Warning, Deprecated moveBy() 1.2 + 4.0 + Warning, Deprecated moveTo() 1.2 + 4.0 + Warning, Deprecated moveToAbsolute() 1.2 + 4.0 + Warning, Deprecated offset() 1.2 + 4.0 + Warning, Deprecated resizeBy() 1.2 + 4.0 + Warning, Deprecated resizeTo() 1.2 + 4.0 + Warning, Deprecated 1291

JavaScript Programmer’s Reference } if (myUserAgent.indexOf(”msie”) != -1) { if (myMajor > 3) { return “ie4″; } return “ie”; } return “other”; } // Start the correct scroller for this browser function startScroller() { eval(getBrowserType() + “_scrollPage()”); } // Browser specific scroller (IE) function ie4_scrollPage() { self.scrollTo(0,theScrollValue); theScrollValue++; if(theScrollValue == theMaxScroll) { theScrollValue = 0; } setTimeout(”ie4_scrollPage()”, 100); } // Browser specific scroller (Navigator) function nav4_scrollPage() { self.document.layer1.moveTo(0,-theScrollValue); theScrollValue++; if(theScrollValue == theMaxScroll) { theScrollValue = 0; } setTimeout(”nav4_scrollPage()”, 20); }

L Layer object (Object/Navigator) Event handling support via properties containing function objects was added to Layer objects at version 1.1 of JavaScript. The example demonstrates how to control a scrolling panel and do it in a way that is cross browser compliant for MSIE and Netscape version 4. There are a lot of issues to deal with, not least the fact that Netscape supports layers but MSIE does not. It is necessary to use layers for scrolling in Netscape because you can only scroll windows or frames in Netscape if they have visible and active scrollbars. Also, the two browsers scroll vertically in opposing directions. If you are careful about the sizing of your objects, and relate the size of the window/frame the layer is drawn in, you can accomplish a continuous scrolling effect by duplicating items from the top of the list to the bottom. Then at an appropriate point, you can jump scroll back to the top of the list. If you do this right, it will appear as if the list is endless and scrolling gently in a continuous loop. This technique is a much simplified example taken from the Video On Demand console at http://www.bbc.co.uk/news where there is a panel showing a listing of live TV programs in a scrolling pane. Warnings: . If you are using layers to position items temporarily on the screen, then you should be careful when using absolute positioning. This can cause the layer to be absolutely positioned relative to the current mouse position and not the window border. The effect is that an item in the positioned layer will appear to follow the mouse as it is clicked. You may need to work out the mouse position and then calculate an offset to relocate the layer where you want it. You may be able to detect the mouse by removing focus from the layer that has the problem, or it may be necessary to create an empty layer which can be safely attached to the mouse. All of these issues are Netscape 4 specific. . Layers are no longer supported in Netscape 6.0. Example code: