Implement canAccess

portal/static/js/gitlab.mjs

@@ -34,7 +34,25 @@
  * to determine if the user is logged in.
  */
 
-async function canAccess(imageUrl) {}
+/**
+ * Checks if the browser can access the image at the given URL. This must be a valid image, otherwise
+ * the check will always fail.
+ *
+ * @param {String} imageUrl A url to an image file (likely hosted on some other origin)
+ */
+async function canAccess(imageUrl) {
+    try {
+        await new Promise((resolve, reject) => {
+            const img = document.createElement("img")
+            img.addEventListener("load", resolve)
+            img.addEventListener("error", reject)
+            img.src = imageUrl
+        })
+        return true
+    } catch {
+        return false
+    }
+}
 
 export async function isLoggedIn() {}