project-manager/doc/js/include.js

import("https://cdn.jsdelivr.net/npm/marked/marked.min.js");
function include(element, file) {
    if (file) {
        const xhttp = new XMLHttpRequest();
        xhttp.onreadystatechange = function () {
            if (this.readyState == 4) {
                if (this.status == 200) {
                    if ('.md' == file.match(/\.md$/)) {
                        element.innerHTML = marked.parse(this.responseText);
                    } else {
                        element.innerHTML = this.responseText;
                    }
                }
                if (this.status == 404) {
                    element.innerHTML = "Page not found.";
                }
            }
        }
        xhttp.open("GET", file, true);
        xhttp.send();
    }
}

function parseIncludes()
{
    const elements = document.querySelectorAll('div[include$=".html"]');
    elements.forEach((element) => {
        include(element, element.getAttribute('include'));
    });
}

function page(file) {
    include(document.getElementById('page'), file);
}

document.addEventListener('DOMContentLoaded', () => {
    parseIncludes();
});