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# YUI Library Examples: Menu Family: Website Top Nav Using Animation With Submenus From JavaScript

# Menu Family: Website Top Nav Using Animation With Submenus From JavaScript

This example demonstrates how to create a traditional, two-column page layout (using Grids) with top navigation featuring animated drop-down menus. The top navigation is created using a MenuBar instance that is constructed using existing markup and enables the user to navigate to different landing pages for each Yahoo! product category. If JavaScript is enabled, submenus are appended to the items in the MenuBar, allowing the user to skip the product landing pages and proceed directly to a given property.

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Begin by placing the markup for the two-column Grid on the page (this example uses the Grids Preset Template 1, 160px left). Add the markup for the root MenuBar instance to the right column of the grid, appending the class of "yuimenubarnav" to the root element. The application of the "yuimenubarnav" class will render each item in the MenuBar instance with arrows to the right of each text label, providing a visual cue that the item contains a submenu.

<div id="productsandservices" class="yuimenubar yuimenubarnav"> <div class="bd"> <ul class="first-of-type"> <li class="yuimenubaritem first-of-type"> <a class="yuimenubaritemlabel" href="#communication">Communication</a> </li> <li class="yuimenubaritem"> <a class="yuimenubaritemlabel" href="http://shopping.yahoo.com">Shopping</a> </li> <li class="yuimenubaritem"> <a class="yuimenubaritemlabel" href="http://entertainment.yahoo.com">Entertainment</a> </li> <li class="yuimenubaritem"> <a class="yuimenubaritemlabel" href="#">Information</a> </li> </ul> </div> </div>

Use the `onContentReady` method of the Event utility to instantiate the MenuBar as soon as its markup is available for scripting.

/* Initialize and render the MenuBar when its elements are ready to be scripted. */ YAHOO.util.Event.onContentReady("productsandservices", function () { /* Instantiate a MenuBar: The first argument passed to the constructor is the id of the element in the page representing the MenuBar; the second is an object literal of configuration properties. */ var oMenuBar = new YAHOO.widget.MenuBar("productsandservices", { autosubmenudisplay: true, hidedelay: 750, lazyload: true }); });

This MenuBar instance makes use of several configuration properties. Setting the "autosubmenudisplay" configuration property to "true" modifies its default behavior so that mousing over any item in the MenuBar automatically triggers the display of its submenu. The "hidedelay" configuration property is set to "750" so each submenu automatically hides 750ms after the user's mouse has left the menu. Lastly, the "lazyload" property is set to "true" to help speed up the initial load time of the MenuBar instance by deferring the initialization and rendering of each submenu until just before it is initially made visible.

Submenus are added to each item in the MenuBar by subscribing to the "beforeRender" event and setting the "submenu" configuration property of each MenuBarItem instance to an object literal containing the necessary data to create the submenu.

/* Define an array of object literals, each containing the data necessary to create a submenu. */ var aSubmenuData = [ { id: "communication", itemdata: [ { text: "360", url: "http://360.yahoo.com" }, { text: "Alerts", url: "http://alerts.yahoo.com" }, { text: "Avatars", url: "http://avatars.yahoo.com" }, { text: "Groups", url: "http://groups.yahoo.com " }, { text: "Internet Access", url: "http://promo.yahoo.com/broadband" }, { text: "PIM", submenu: { id: "pim", itemdata: [ { text: "Yahoo! Mail", url: "http://mail.yahoo.com" }, { text: "Yahoo! Address Book", url: "http://addressbook.yahoo.com" }, { text: "Yahoo! Calendar", url: "http://calendar.yahoo.com" }, { text: "Yahoo! Notepad", url: "http://notepad.yahoo.com" } ] } }, { text: "Member Directory", url: "http://members.yahoo.com" }, { text: "Messenger", url: "http://messenger.yahoo.com" }, { text: "Mobile", url: "http://mobile.yahoo.com" }, { text: "Flickr Photo Sharing", url: "http://www.flickr.com" }, ] }, { id: "shopping", itemdata: [ { text: "Auctions", url: "http://auctions.shopping.yahoo.com" }, { text: "Autos", url: "http://autos.yahoo.com" }, { text: "Classifieds", url: "http://classifieds.yahoo.com" }, { text: "Flowers & Gifts", url: "http://shopping.yahoo.com/b:Flowers%20%26%20Gifts:20146735" }, { text: "Real Estate", url: "http://realestate.yahoo.com" }, { text: "Travel", url: "http://travel.yahoo.com" }, { text: "Wallet", url: "http://wallet.yahoo.com" }, { text: "Yellow Pages", url: "http://yp.yahoo.com" } ] }, { id: "entertainment", itemdata: [ { text: "Fantasy Sports", url: "http://fantasysports.yahoo.com" }, { text: "Games", url: "http://games.yahoo.com" }, { text: "Kids", url: "http://www.yahooligans.com" }, { text: "Music", url: "http://music.yahoo.com" }, { text: "Movies", url: "http://movies.yahoo.com" }, { text: "Radio", url: "http://music.yahoo.com/launchcast" }, { text: "Travel", url: "http://travel.yahoo.com" }, { text: "TV", url: "http://tv.yahoo.com" } ] }, { id: "information", itemdata: [ { text: "Downloads", url: "http://downloads.yahoo.com" }, { text: "Finance", url: "http://finance.yahoo.com" }, { text: "Health", url: "http://health.yahoo.com" }, { text: "Local", url: "http://local.yahoo.com" }, { text: "Maps & Directions", url: "http://maps.yahoo.com" }, { text: "My Yahoo!", url: "http://my.yahoo.com" }, { text: "News", url: "http://news.yahoo.com" }, { text: "Search", url: "http://search.yahoo.com" }, { text: "Small Business", url: "http://smallbusiness.yahoo.com" }, { text: "Weather", url: "http://weather.yahoo.com" } ] } ]; /* Subscribe to the "beforerender" event, adding a submenu to each of the items in the MenuBar instance. */ oMenuBar.subscribe("beforeRender", function () { if (this.getRoot() == this) { this.getItem(0).cfg.setProperty("submenu", aSubmenuData[0]); this.getItem(1).cfg.setProperty("submenu", aSubmenuData[1]); this.getItem(2).cfg.setProperty("submenu", aSubmenuData[2]); this.getItem(3).cfg.setProperty("submenu", aSubmenuData[3]); } }); /* Call the "render" method with no arguments since the markup for this MenuBar instance is already exists in the page. */ oMenuBar.render();

Setup the animation for the submenus by subscribing to their "beforeShow" and "show" events. The "beforeShow" event handler will be used to collapse the height of the Menu instance before it is made visible. The "show" event handler will kick off an animation that increments the "marginTop" style property of each submenu's `<ul>` element from a negative value equal to its height to 0, causing the submenu to slowly expand to its original height as it is displayed.

var Dom = YAHOO.util.Dom, oAnim; // Animation instance /* "beforeshow" event handler for each submenu of the MenuBar instance, used to setup certain style properties before the menu is animated. */ function onSubmenuBeforeShow(p_sType, p_sArgs) { var oBody, oShadow, oUL; if (this.parent) { /* Get a reference to the Menu's shadow element and set its "height" property to "0px" to syncronize it with the height of the Menu instance. */ oShadow = this.element.lastChild; oShadow.style.height = "0px"; /* Stop the Animation instance if it is currently animating a Menu. */ if (oAnim && oAnim.isAnimated()) { oAnim.stop(); oAnim = null; } /* Set the body element's "overflow" property to "hidden" to clip the display of its negatively positioned <ul> element. */ oBody = this.body; /* There is a bug in gecko-based browsers where an element whose "position" property is set to "absolute" and "overflow" property is set to "hidden" will not render at the correct width when its offsetParent's "position" property is also set to "absolute." It is possible to work around this bug by specifying a value for the width property in addition to overflow. */ if (this.parent && !(this.parent instanceof YAHOO.widget.MenuBarItem) && YAHOO.env.ua.gecko) { Dom.setStyle(oBody, "width", (oBody.clientWidth + "px")); } Dom.setStyle(oBody, "overflow", "hidden"); /* Set the <ul> element's "marginTop" property to a negative value so that the Menu's height collapses. */ oUL = oBody.getElementsByTagName("ul")[0]; Dom.setStyle(oUL, "marginTop", ("-" + oUL.offsetHeight + "px")); } } /* "tween" event handler for the Anim instance, used to syncronize the size and position of the Menu instance's shadow and iframe shim (if it exists) with its changing height. */ function onTween(p_sType, p_aArgs, p_oShadow) { if (this.cfg.getProperty("iframe")) { this.syncIframe(); } if (p_oShadow) { p_oShadow.style.height = this.element.offsetHeight + "px"; } } /* "complete" event handler for the Anim instance, used to remove style properties that were animated so that the Menu instance can be displayed at its final height. */ function onAnimationComplete(p_sType, p_aArgs, p_oShadow) { var oBody = this.body, oUL = oBody.getElementsByTagName("ul")[0]; if (p_oShadow) { p_oShadow.style.height = this.element.offsetHeight + "px"; } Dom.setStyle(oUL, "marginTop", ""); Dom.setStyle(oBody, "overflow", ""); if (this.parent && !(this.parent instanceof YAHOO.widget.MenuBarItem) && YAHOO.env.ua.gecko) { Dom.setStyle(oBody, "width", ""); } } /* "show" event handler for each submenu of the MenuBar instance - used to kick off the animation of the <ul> element. */ function onSubmenuShow(p_sType, p_sArgs) { var oElement, oShadow, oUL; if (this.parent) { oElement = this.element; oShadow = oElement.lastChild; oUL = this.body.getElementsByTagName("ul")[0]; /* Animate the <ul> element's "marginTop" style property to a value of 0. */ oAnim = new YAHOO.util.Anim(oUL, { marginTop: { to: 0 } }, .5, YAHOO.util.Easing.easeOut); oAnim.onStart.subscribe(function () { oShadow.style.height = "100%"; }); oAnim.animate(); /* Subscribe to the Anim instance's "tween" event for IE to syncronize the size and position of a submenu's shadow and iframe shim (if it exists) with its changing height. */ if (YAHOO.env.ua.ie) { oShadow.style.height = oElement.offsetHeight + "px"; /* Subscribe to the Anim instance's "tween" event, passing a reference Menu's shadow element and making the scope of the event listener the Menu instance. */ oAnim.onTween.subscribe(onTween, oShadow, this); } /* Subscribe to the Anim instance's "complete" event, passing a reference Menu's shadow element and making the scope of the event listener the Menu instance. */ oAnim.onComplete.subscribe(onAnimationComplete, oShadow, this); } } /* Subscribe to the "beforerender" event, adding a submenu to each of the items in the MenuBar instance. */ oMenuBar.subscribe("beforeRender", function () { if (this.getRoot() == this) { this.getItem(0).cfg.setProperty("submenu", aSubmenuData[0]); this.getItem(1).cfg.setProperty("submenu", aSubmenuData[1]); this.getItem(2).cfg.setProperty("submenu", aSubmenuData[2]); this.getItem(3).cfg.setProperty("submenu", aSubmenuData[3]); } }); /* Subscribe to the "beforeShow" and "show" events for each submenu of the MenuBar instance. */ oMenuBar.subscribe("beforeShow", onSubmenuBeforeShow); oMenuBar.subscribe("show", onSubmenuShow);

### Menu Family Examples:

- Basic Menu From Markup
- Basic Menu From JavaScript
- Grouped Menu Items Using Markup
- Grouped Menu Items Using JavaScript
- Grouped Menu Items With Titles From Markup
- Grouped Menu Items With Titles From JavaScript
- Multi-tiered Menu From Markup
- Multi-tiered Menu From JavaScript
- Handling Menu Click Events
- Listening For Menu Events
- MenuItem Configuration Properties
- Setting Menu Configuration Properties At Runtime
- Website Left Nav With Submenus Built From Markup
- Website Left Nav With Submenus From JavaScript
- Website Top Nav With Submenus Built From Markup
- Website Top Nav With Submenus From JavaScript
- Website Left Nav Using Animation With Submenus Built From Markup
- Website Left Nav Using Animation With Submenus From JavaScript
- Website Top Nav Using Animation With Submenus Built From Markup
- Website Top Nav Using Animation With Submenus From JavaScript
- Context Menu
- Adding A Context Menu To A Table
- Adding A Context Menu To A TreeView
- OS-Style Programs Menu
- Application Menubar
- Context Menu Integration (included with examples for DataTable Control (beta))
- Menu Buttons (included with examples for Button Control)
- Split Buttons (included with examples for Button Control)
- Calendar Menu Button (included with examples for Button Control)
- Calendar Split Button (included with examples for Button Control)
- Color Picker Button (included with examples for Button Control)
- Fixed Width Menu Button (included with examples for Button Control)
- Slider Button (included with examples for Button Control)

### More Menu Family Resources:

- User's Guide (external)
- API Documentation
- Cheat Sheet PDF (external)

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