A light spiritual successor to neon-animated-pages using only css animations

Usage no npm install needed!

<script type="module">
  import heliumAnimatedPages from 'https://cdn.skypack.dev/helium-animated-pages';



Published on webcomponents.orgnpm version


This is a light spiritual successor to the now deprecated <neon-animated-pages>.

It works with CSS animations and only depends on lit. So, you don't have to worry about including any heavy JS libraries.

This component takes care of the logic behind triggering the animations so that you can focus on making your views and your animations. Alternatively, you can use the animations included in the sample-animations folder. 😉

To begin using it follow these simple steps:

  • Install it:

    npm i --save helium-animated-pages

  • Import the script:

    In html:

    <!-- type="module" is essential -->
    <script type="module" src="node_modules/helium-animated-pages"></script>

    In a js module:

    import 'helium-animated-pages';
  • Create an instance of <helium-animated-pages> in your HTML page. You can also use any framework that supports rendering Custom Elements.

        Define your animation keyframes and classes
          in the same context that contains
        You can also use the provided sample animations.
        The sample code here only uses a simple
          fade animation to keep the code short.
      .page-fadeIn {
        animation: fadeIn 0.7s ease both;
      @keyframes fadeIn {
        from {
          opacity: 0.3;
        to {
      .page-fadeOut {
        animation: fadeOut 0.7s ease both;
      @keyframes fadeOut {
        from {
        to {
          opacity: 0;
      <h2>Select a page</h2>
      <select id="selector">
        <option value="page1">Page 1</option>
        <option value="page2">Page 2</option>
        <option value="page3">Page 3</option>
      Use attrForSelected to define which attribute will
        act as the identifier for the pages.
      You can also opt to not use it and use numerical indexes instead.
    <helium-animated-pages id="pages" attrForSelected="name">
      <!-- The pages can be almost anything -->
      <section name="page1">Page 1</section>
      <div name="page2">Page 2</div>
      <custom-element name="page3"></custom-element>
        Here's a sample way of switching pages.
        You can use a router to do this switching.
      document.querySelector('#selector').addEventListener('change', e => {
        // Switch pages; you can use the numerical index too.
        document.querySelector('#pages').selected = e.target.value;
        Here we define the "rules" about which CSS classes
          should be applied on the different page transitions.
        For more info go to:
        I'm using CSS classes that aren't actually defined in
          this context for illustrative purposes.
        You must define every class that you want to use.
      document.querySelector('#pages').animationClasses = {
          The animation classes rules are like CSS rules:
            the most specific ones apply first.
        // from page1 to page2
        page1_page2: {
          in: 'page_moveFromRight',
          out: 'page_moveToLeft',
        // from anything other than page1 to page2
        '*_page2': {
          in: 'page_moveFromLeft',
          out: 'page_moveToRight',
        // from page1 to anything other than page2
        'page1_*': {
          in: 'page_moveFromTop',
          out: 'page_moveToBottom',
        // from nothing selected to page1
        _page1: {
          in: 'page_moveFromBottom',
          out: 'page_moveToTop',
        // fallback in case none of the rules above apply
        default: {
          in: 'page-fadeIn',
          out: 'page-fadeOut',