index.js

function getVersionPath(path, versions, defaultVersion) {
    /**
     * If the path is /, /README.md or /index.html, we want to redirect to the default version.
     * Otherwise, we want to redirect to the versioned path.
     */
    const parts = path.split('/');
    const version = versions.find((v) => v.folder === parts[1]);
    return version ? version.folder : defaultVersion;
  }

function versionedDocsPlugin(hook, vm) {
    var versions = vm.config.versions || [];
    var defaultVersion = vm.config.versions.find((v) => v.default).folder;
    
    function updateVersion(version) {
        var newPath = vm.route.path.split('/').slice(2).join('/');
        if (newPath === '' || newPath === 'README.md') {
          newPath = '/';
        }
        window.location.href = '/' + version + newPath;
        vm.basePath = '/' + version + newPath;
    }

    function initVersionSelector() {
        // Version selector
        var selector = document.createElement('div');
        selector.className = 'version-selector';
        selector.innerHTML = `
        <select>
            ${versions
            .map(
                (v) =>
                `<option value="${v.folder}" ${
                    v.default ? 'selected' : ''
                }>${v.label}</option>`
            )
            .join('')}
        </select>
        `;
        
        // Adding event listener
        var versionPath = (window.location.pathname && window.location.pathname.split('/')[1]) || defaultVersion;
        selector.querySelector('select').value = versionPath;
        selector.querySelector('select').addEventListener('change', function () {
            updateVersion(this.value);
        });

        // Adding label
        var labelText = vm.config.versionSelectorLabel || 'Version:';
        var label = document.createElement('span');
        label.className = 'version-selector-label';
        label.textContent = labelText;
        selector.insertBefore(label, selector.querySelector('select'));
        
        var nameEl = document.querySelector('.app-name');
        if (nameEl) {
            var versionLabel = versions.find((v) => v.folder === versionPath).label;
            nameEl.innerHTML += ` <small>${versionLabel}</small>`;
            nameEl.parentNode.insertBefore(selector, nameEl.nextElementSibling);
        }
        return selector;
    }
 
    hook.ready(function () {       
        // Set coverpage to false if it's not a versioned coverpage
        if (vm.route.path !== '/_coverpage.md') {
            vm.config.coverpage = false;
        }

        // Initialize the version selector
        versionSelector = initVersionSelector();
    });

    hook.beforeEach(function (html, next) {
        // Replace {{versionLabel}} with the current version label in all markdown files
        var versionPath = getVersionPath(vm.compiler.contentBase, versions, defaultVersion);
        var version = versions.find((v) => v.folder === versionPath);
        
        if (version) {
          var versionLabel = version.label;
          var updatedHtml = html.replace(/{{versionLabel}}/g, versionLabel);
          next(updatedHtml);
        } else {
          next(html);
        }
      });

      hook.doneEach(function () {
        // Replace {{versionLabel}} with the current version label in coverpage
        var versionPath = getVersionPath(vm.compiler.contentBase, versions, defaultVersion);
        var version = versions.find((v) => v.folder === versionPath);
        
        if (version) {
          var versionLabel = version.label;
          var cover = document.querySelector('.cover');
          if (cover) {
            cover.innerHTML = cover.innerHTML.replace(/{{versionLabel}}/g, versionLabel);
          }
        }
      });
}

window.$docsify.plugins = [].concat(versionedDocsPlugin, window.$docsify.plugins);

(function() {
    if (window.location.pathname === '/' || window.location.pathname === '/index.html') {
      var defaultVersion = window.$docsify.versions.find((v) => v.default).folder;
      window.location.replace('/' + defaultVersion + '/');
    }
  })();