alfresco-ng2-components/demo-shell-ng2/app/web-components/helloworld/helloworld.html

<!-- Defines element markup -->
<template>
    <p>Hello <strong></strong> :)</p>
    <content></content>
</template>

<script>
    (function (window, document, undefined) {
        // Refers to the "importer", which is index.html
        var thatDoc = document;

        // Refers to the "importee", which is src/hello-world.html
        var thisDoc =  (thatDoc._currentScript || thatDoc.currentScript).ownerDocument;

        // Gets content from <template>
        var template = thisDoc.querySelector('template').content;

        // Creates an object based in the HTML Element prototype
        var _text = '_text';
        var MyElementProto = Object.create(HTMLElement.prototype, {
            text: {
                get: function() { return _text; },
                set: function(newValue) {
                    _text = newValue;
                    this.setText(newValue);
                }
            }
        });

        // Fires when an instance of the element is created
        MyElementProto.createdCallback = function() {
            // Creates the shadow root
            var shadowRoot = this.createShadowRoot();
            // Adds a template clone into shadow root
            var clone = thatDoc.importNode(template, true);
            shadowRoot.appendChild(clone);
            // Caches <strong> DOM query
            this.strong = shadowRoot.querySelector('strong');

            // Checks if the "text" attribute has been overwritten
            /*
            if (this.hasAttribute('text')) {
                var text = this.getAttribute('text');
                this.setText(text);
            }
            else {
                this.setText(this.text);
            }
            */
        };

        // Fires when an attribute was added, removed, or updated
        MyElementProto.attributeChangedCallback = function(attr, oldVal, newVal) {
            if (attr === 'text') {
                this.setText(newVal);
            }
        };

        MyElementProto.setText = function(val) {
            _text = val;
            this.strong.textContent = val;
        };

        // Registers <hello-world> in the main document
        window.MyElement = thatDoc.registerElement('hello-world', {
            prototype: MyElementProto
        });
    })(window, document);
</script>