用户通过点击页面左侧的菜单，对应的页面加载时伴随着滑动过滤动画，并带有进度条效果。当然页面的加载是Ajax驱动的，整个加载过渡过程非常流畅，非常好的用户体验。

HTML

HTML结构中，.cd-main包含页面主体内容，.cd-side-navigation包含着侧边导航条，#cd-loading-bar则是用来做进度条动画用的。

<nav class="cd-side-navigation"> <ul> <li> <a href="index.html" class="selected" data-menu="index"> <svg><!-- svg content here --></svg> Intro </a> </li> <li> <!-- ... --> </li> <!-- other list items here --> </ul> </nav> <!-- .cd-dashboard --> <main class="cd-main"> <section class="cd-section index visible"> <header> <div class="cd-title"> <h2>Animated Page Transition #2</h2> <span>Some text here</span> </div> <a href="#index-content" class="cd-scroll">Scroll Down</a> </header> <div class="cd-content" id="index-content"> <!-- content here --> </div> <!-- .cd-content --> </section> <!-- .cd-section --> </main> <!-- .cd-main --> <div id="cd-loading-bar" data-scale="1" class="index"></div> <!-- lateral loading bar -->

CSS

我们将.cd-side-navigation固定在页面左侧，并且设置它的高度为100%，这样左侧导航菜单就始终占据左侧边栏，右侧主体内容滚动时，左侧导航菜单不动。

.cd-side-navigation { position: fixed; z-index: 3; top: 0; left: 0; height: 100vh; width: 94px; overflow: hidden; } .cd-side-navigation ul { height: 100%; overflow-y: auto; } .cd-side-navigation::before { content: ''; position: absolute; top: 0; left: 0; height: 100%; width: calc(100% - 4px); background-color: #131519; } .cd-side-navigation li { width: calc(100% - 4px); } .cd-side-navigation a { display: block; position: relative; } .cd-side-navigation a::after { content: ''; position: absolute; top: 0; right: -4px; height: 100%; width: 4px; background-color: #83b0b9; opacity: 0; } .no-touch .cd-side-navigation a:hover::after { opacity: 1; }

JavaScript

当我们点击左侧菜单时，调用triggerAnimation()函数，这个函数会触发加载进度条动画函数loadingBarAnimation()，接着加载页面内容函数：loadNewContent()。

function loadingBarAnimation() { var scaleMax = loadingBar.data('scale'); if( scaleY + 1 < scaleMax) { newScaleValue = scaleY + 1; } // ... loadingBar.velocity({ scaleY: newScaleValue }, 100, loadingBarAnimation); }

当新页面被选中时，一个新的元素.cd-section将会被创建并且插入到DOM中，然后load()新的url内容。

function loadNewContent(newSection) { var section = $('<section class="cd-section overflow-hidden '+newSection+'"></section>').appendTo(mainContent); //load the new content from the proper html file section.load(newSection+'.html .cd-section > *', function(event){ loadingBar.velocity({ scaleY: scaleMax //this is the scaleY value to cover the entire window height (100% loaded) }, 400, function(){ section.addClass('visible'); var url = newSection+'.html'; if(url!=window.location){ //add the new page to the window.history window.history.pushState({path: url},'',url); } // ... }); }); }

通过异步加载的页面要返回上一页历史浏览记录的话，可以点击浏览器上的返回即可。返回上一页同样有过渡动画效果。