jquery特效 翻转导航栏

 

Step 1. Wireframe – HTML

This part is very simple. Your typical unordered list with links.

<ul id="topnav">    <li><a href="#">Home</a></li>    <li><a href="#">Services</a></li>    <li><a href="#">Portfolio</a></li>    <li><a href="#">Blog</a></li>    <li><a href="#">About</a></li>    <li><a href="#">Contact</a></li></ul>

Step 2. Styling – CSS

Only thing special about the below properties will be that each list item has an overflow of hidden to imitate the masking technique. Check out the image below to see what I mean.

Notice there were no duplicate <span> tags in the markup in step 1. We will be adding that later with a few lines of jQuery.

ul#topnav {margin: 0;padding: 0;list-style: none;float: left;font-size: 1.1em;}ul#topnav li{margin: 0;padding: 0;overflow: hidden;  /*--Important - Masking out the hover state by default--*/float: left;height:40px;}ul#topnav a, ul#topnav span { /*--The <a> and <span> share the same properties since the <span>  will be a duplicate of the <a> tag--*/padding: 10px 20px;float: left;text-decoration: none;color: #fff;background: url(a_bg.gif) repeat-x;text-transform: uppercase;clear: both;width: 100%;height: 20px;line-height: 20px; /*--Vertical alignment of text--*/}ul#topnav a{ /*--This is basically the hover state of navigation--*/color: #555;background-position: left bottom;}ul#topnav span{ /*--Default state of navigation--*/background-position: left top;}

Step 3. Animation – jQuery

For those who are not familiar with jQuery, do check out their site first and get an overview of how it works. I’ve shared a few tricks that I have picked up along the way, you can check those out as well.

Initial Step – Call the jQuery file

You can choose to download the file from the jQuery site, or you can use this one hosted on Google.

<script type="text/javascript"src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>

As you can see below, we are duplicating the span tags, then animating them -40px to the top to shift the navigation.

The following script contains comments explaining which jQuery actions are being performed.

$(document).ready(function() {$("#topnav li").prepend("<span></span>"); //Throws an empty span tag right before the a tag$("#topnav li").each(function() { //For each list item...var linkText = $(this).find("a").html(); //Find the text inside of the <a> tag$(this).find("span").show().html(linkText); //Add the text in the <span> tag}); $("#topnav li").hover(function() {//On hover...$(this).find("span").stop().animate({marginTop: "-40" //Find the <span> tag and move it up 40 pixels}, 250);} , function() { //On hover out...$(this).find("span").stop().animate({marginTop: "0"  //Move the <span> back to its original state (0px)}, 250);});});

 

 

http://www.sohtanaka.com/web-design/animate-navigation-with-css-jquery/

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