Parse an HTML string into a document fragment

parse-html.js

const cache = new Map();
const template = document.createElement('template');

function parseHTML(html) {
    if (cache.has(html)) {
        return cache.get(html).cloneNode(true);
    }
    template.innerHTML = html;
    cache.set(html, template.content);
    return cache.get(html).cloneNode(true);
}