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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              <template id="myheadingtemplate">
  <div>
    <i class="icon"></i>
    <h1>
      <content></content>
    </h1>
    <a href="#" >#</a>
  </div>
  <style>
      i.icon:before {font-size:30px;}
      i.user:before {content: '☻';}
      i.pentagon:before {content: '⬟';}
      h1 {display: inline-block;}
  </style>
</template>

<template id="myblocktemplate">
  <div>
    <my-heading></my-heading>
    <content></content>
  </div>
  <style>
     div {
       border: 1px solid #000;
       padding: 5%;
       margin-bottom: 5%;
     }
  </style>
</template>

<my-block>
  <my-block heading-icon="user" heading="My important heading" >
    <div>Lorem ipsum</div>
    <!-- Notice how this does not get a border -->
  </my-block>

  <my-block heading-icon="pentagon" heading="My second heading" >
    Lorem ipsum
  </my-block>
</my-block>
            
          
!
            
              my-block div {
  color: green;
}

my-block my-block {
  color: red;
}
            
          
!
            
              /**
 * Create callback
 * @callback createElementCallback
 * @param {element} shaddow the shadow dom element
 * @param {scope} this the scope of the custom element
 */

/**
 * Generates a new component
 * @param {string} elementName Name of JavaScript Class for the element
 * @param {string} tagName Name of the tag produced (Must contain at least one '-')
 * @param {string} templateSelector Selector to template for the contents of the shadow DOM
 * @param {createElementCallback} postCreateCallback Callback triggered on construction of the element
 */
function generateComponent(elementName, tagName, templateSelector, postCreateCallback) {

  //Create a custom element that extends from the base HTMLElement
  var elementPrototype = Object.create(HTMLElement.prototype);

  //On creation of an element this code triggers
  //Defines a shadow root within our custom element
  //Imports in the matching template
  //Triggers the callback for any further customisation
  elementPrototype.createdCallback = function() {
    var shadow = this.createShadowRoot();
    var template = document.querySelector(templateSelector);
    var clone = document.importNode(template.content, true);
    shadow.appendChild(clone);
    if (postCreateCallback) { postCreateCallback(shadow, this); }
  };

  //Register the element name to the window
  window[elementName] = document.registerElement(tagName, {prototype: elementPrototype});
}

function slugify(slug) {
  return slug.toLowerCase().replace(/\s/g,'-');
}

generateComponent('MyBlockElement', 'my-block', '#myblocktemplate', function (shadow, scope) {
  var headingDOM = shadow.querySelector('my-heading');
  var heading = scope.getAttribute('heading');
  var icon = scope.getAttribute('heading-icon');
  if (headingDOM) {
    if (heading) {
      headingDOM.innerText = heading;
    } else {
      headingDOM.style.display = 'none';
    }
    if (icon) {
      headingDOM.setAttribute('icon', icon);
    }
  }
});

generateComponent('MyHeadingElement', 'my-heading', '#myheadingtemplate', function (shadow, scope) {
  var icon = scope.getAttribute('icon');
  var iconDOM = shadow.querySelector('i');
  var linkDOM = shadow.querySelector('a');
  if (icon && iconDOM) {
    iconDOM.classList.add(icon);
  }
  if (linkDOM && scope.innerText !== '') {
      linkDOM.setAttribute('href', '#' + slugify(scope.innerText));
  }
});


            
          
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