diff --git a/packages/runtimes/js/src/helpers/bundle-url-common.js b/packages/runtimes/js/src/helpers/bundle-url-common.js
index 089675b22..8a44855a8 100644
--- a/packages/runtimes/js/src/helpers/bundle-url-common.js
+++ b/packages/runtimes/js/src/helpers/bundle-url-common.js
@@ -1,4 +1,8 @@
-// Get the URL without the filename (last / segment)
+/** Get the URL without the filename (last / segment)
+ *
+ * @param {string} url
+ * @returns {string} The URL with the file name removed
+ */
 function getBaseURL(url) {
   return url.slice(0, url.lastIndexOf('/')) + '/';
 }
diff --git a/packages/runtimes/js/src/helpers/bundle-url-shards.js b/packages/runtimes/js/src/helpers/bundle-url-shards.js
index d1d695ef0..dfdde69ea 100644
--- a/packages/runtimes/js/src/helpers/bundle-url-shards.js
+++ b/packages/runtimes/js/src/helpers/bundle-url-shards.js
@@ -2,6 +2,15 @@ const {getBaseURL, stackTraceUrlRegexp} = require('./bundle-url-common');
 
 const bundleURL = {};
 
+/**
+ * Retrieves the sharded bundle URL based on the bundle name and the maximum number of shards.
+ *
+ * @param {string} bundleName - The file name of the requested bundle.
+ * @param {number} maxShards - The maximum number of domain shards available.
+ * @param {Error} inputError - An error object to extract the stack trace from
+ * (for testing purposes).
+ * @returns {string} The URL of the sharded bundle, without file name.
+ */
 function getShardedBundleURL(bundleName, maxShards, inputError) {
   let value = bundleURL[bundleName];
 
diff --git a/packages/runtimes/js/src/helpers/bundle-url.js b/packages/runtimes/js/src/helpers/bundle-url.js
index 341ee41a0..bbd4161b3 100644
--- a/packages/runtimes/js/src/helpers/bundle-url.js
+++ b/packages/runtimes/js/src/helpers/bundle-url.js
@@ -2,6 +2,13 @@ const {getBaseURL, stackTraceUrlRegexp} = require('./bundle-url-common');
 
 const bundleURL = {};
 
+/**
+ * Retrieves the cached bundle URL for a given identifier.
+ * If the URL is not cached, it computes and stores it in the cache.
+ *
+ * @param {string} id - The identifier for the bundle.
+ * @returns {string} The URL of the bundle, without file name.
+ */
 function getBundleURLCached(id) {
   let value = bundleURL[id];
 
@@ -28,6 +35,10 @@ function getBundleURL() {
   return '/';
 }
 
+/**
+ * @param {string} url
+ * @returns {string}
+ */
 function getOrigin(url) {
   return new URL(url).origin;
 }