html2canvas/tests/reftests/webcomponents/slot-element.js

customElements.define('summary-display',
    class extends HTMLElement {
        constructor() {
            super();

            const template = document.getElementById('summary-display-template');
            const templateContent = template.content;

            const shadowRoot = this.attachShadow({mode: 'open'});
            shadowRoot.appendChild(templateContent.cloneNode(true));

            const items = Array.from(this.querySelectorAll('li'));
            const descriptions = Array.from(this.querySelectorAll('p'));

            items.forEach(item => {
                handleClick(item);
            });

            descriptions.forEach(description => {
                updateDisplay(description, items[1]);
            });

            function handleClick(item) {
                item.addEventListener('click', function() {
                    items.forEach(item => {
                        item.style.backgroundColor = 'white';
                    });

                    descriptions.forEach(description => {
                        updateDisplay(description, item);
                    });
                });
            }

            function updateDisplay(description, item) {
                description.removeAttribute('slot');

                if(description.getAttribute('data-name') === item.textContent) {
                    description.setAttribute('slot', 'choice');
                    item.style.backgroundColor = '#bad0e4';
                }
            }

            const slots = this.shadowRoot.querySelectorAll('slot');
            slots[1].addEventListener('slotchange', function(e) {
                const nodes = slots[1].assignedNodes();
                console.log(`Element in Slot "${slots[1].name}" changed to "${nodes[0].outerHTML}".`);
            });
        }
    }
);