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TopUponDisplay

Description:

JavaScript code to be executed each time the menu is displayed as a top level menu.

Value:

null, or String JavaScript expression.

Applies To:

Menus.

Browser Compatibility:

TopUponDisplay is supported in all browsers.

Comments:

This parameter defines JavaScript code that should be executed when the menu is being displayed as a top level menu. Compare this parameter to ChildUponDisplay, which defines JavaScript code that should be executed when the menu is being displayed as a child menu. A single menu can be used as both a top level menu and a child menu on the same page. This Child vs. Top distinction allows you to define different JavaScript code depending on how the menu is currently being utilized.

When using a String JavaScript expression (i.e., a JavaScript expression contained within quotes), that expression will not be evaluated until just before the menu is displayed. It will then be reevaluated every time the menu is redisplayed.

HierMenus version 6 provides a custom function in the HM_Loader.js file that can be particularly useful when called from the UponDisplay and UponHide parameters: HM_f_ToggleElementList, which allows you to hide select elements, or other windowed page elements that may be overlapping your menus (see FAQ #1). A detailed explanation of HM_f_ToggleElementList along with a working example can be found in Bulletin 6. Another common use of TopUponDisplay and TopUponHide is to synchronize link rollover effects with the appearance and hiding of menus. This topic is discussed in detail in Bulletin 12.

Examples:

// Ok:
TopUponDisplay:null,       // cancel inherited UponDisplay
TopUponDisplay:"HM_f_ToggleElementList(false,['select'],'tag')", 
       // hide all select elements

// Incorrect:
TopUponDisplay:"null",     // no quotes around null
TopUponDisplay:HM_f_ToggleElementList(false,['select'],'tag'),
       // must have quotes around String JavaScript Expressions

Default:

null

See Also:

TopUponHide, ChildUponDisplay, ChildUponHide, Bulletin 6: Hiding Page Elements, Bulletin 12: Synchronizing Link Rollovers