1 files changed, 127 insertions, 0 deletions
diff --git a/v1.55/docs/website_files/version-picker.js b/v1.55/docs/website_files/version-picker.js
new file mode 100644
index 0000000000..bb35a7d896
--- /dev/null
+++ b/v1.55/docs/website_files/version-picker.js
@@ -0,0 +1,127 @@
+
+const dropdown = document.querySelector('.version-picker .dropdown');
+const dropdownMenu = dropdown.querySelector('.dropdown-menu');
+
+fetchVersions(dropdown, dropdownMenu).then(() => {
+    initializeVersionDropdown(dropdown, dropdownMenu);
+});
+
+/**
+ * Initialize the dropdown functionality for version selection.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ */
+function initializeVersionDropdown(dropdown, dropdownMenu) {
+    // Toggle the dropdown menu on click
+    dropdown.addEventListener('click', function () {
+        this.setAttribute('tabindex', 1);
+        this.classList.toggle('active');
+        dropdownMenu.style.display = (dropdownMenu.style.display === 'block') ? 'none' : 'block';
+    });
+  
+    // Remove the 'active' class and hide the dropdown menu on focusout
+    dropdown.addEventListener('focusout', function () {
+        this.classList.remove('active');
+        dropdownMenu.style.display = 'none';
+    });
+  
+    // Handle item selection within the dropdown menu
+    const dropdownMenuItems = dropdownMenu.querySelectorAll('li');    
+    dropdownMenuItems.forEach(function (item) {
+        item.addEventListener('click', function () {
+            dropdownMenuItems.forEach(function (item) {
+                item.classList.remove('active');
+            });
+            this.classList.add('active');
+            dropdown.querySelector('span').textContent = this.textContent;
+            dropdown.querySelector('input').value = this.getAttribute('id');
+
+            window.location.href = changeVersion(window.location.href, this.textContent);
+        });
+    });
+};
+
+/**
+ * This function fetches the available versions from a GitHub repository
+ * and inserts them into the version picker.
+ * 
+ * @param {Element} dropdown - The dropdown element.
+ * @param {Element} dropdownMenu - The dropdown menu element.
+ * @returns {Promise<Array<string>>} A promise that resolves with an array of available versions.
+ */
+function fetchVersions(dropdown, dropdownMenu) {
+    return new Promise((resolve, reject) => {
+        window.addEventListener("load", () => {
+
+            fetch("https://api.github.com/repos/matrix-org/synapse/git/trees/gh-pages", {
+                cache: "force-cache",
+            }).then(res => 
+                res.json()
+            ).then(resObject => {
+                const excluded = ['dev-docs', 'v1.91.0', 'v1.80.0', 'v1.69.0'];
+                const tree = resObject.tree.filter(item => item.type === "tree" && !excluded.includes(item.path));
+                const versions = tree.map(item => item.path).sort(sortVersions);
+
+                // Create a list of <li> items for versions
+                versions.forEach((version) => {
+                    const li = document.createElement("li");
+                    li.textContent = version;
+                    li.id = version;
+    
+                    if (window.SYNAPSE_VERSION === version) {
+                        li.classList.add('active');
+                        dropdown.querySelector('span').textContent = version;
+                        dropdown.querySelector('input').value = version;
+                    }
+    
+                    dropdownMenu.appendChild(li);
+                });
+
+                resolve(versions);
+
+            }).catch(ex => {
+                console.error("Failed to fetch version data", ex);
+                reject(ex);
+            })
+        });
+    });
+}
+
+/**
+ * Custom sorting function to sort an array of version strings.
+ *
+ * @param {string} a - The first version string to compare.
+ * @param {string} b - The second version string to compare.
+ * @returns {number} - A negative number if a should come before b, a positive number if b should come before a, or 0 if they are equal.
+ */
+function sortVersions(a, b) {
+    // Put 'develop' and 'latest' at the top
+    if (a === 'develop' || a === 'latest') return -1;
+    if (b === 'develop' || b === 'latest') return 1;
+
+    const versionA = (a.match(/v\d+(\.\d+)+/) || [])[0];
+    const versionB = (b.match(/v\d+(\.\d+)+/) || [])[0];
+
+    return versionB.localeCompare(versionA);
+}
+
+/**
+ * Change the version in a URL path.
+ *
+ * @param {string} url - The original URL to be modified.
+ * @param {string} newVersion - The new version to replace the existing version in the URL.
+ * @returns {string} The updated URL with the new version.
+ */
+function changeVersion(url, newVersion) {
+    const parsedURL = new URL(url);
+    const pathSegments = parsedURL.pathname.split('/');
+  
+    // Modify the version
+    pathSegments[2] = newVersion;
+
+    // Reconstruct the URL
+    parsedURL.pathname = pathSegments.join('/');
+  
+    return parsedURL.href;
+}
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