web: add uuid() function with fallback if randomUUID is missing

web/src/lib/util.ts

@@ -26,3 +26,20 @@ export const ffmpegMetadataArgs = (metadata: CobaltFileMetadata) =>
         }
         return [];
     });
+
+const digit = () => '0123456789abcdef'[Math.random() * 16 | 0];
+export const uuid = () => {
+    if (typeof crypto !== 'undefined' && 'randomUUID' in crypto) {
+        return crypto.randomUUID();
+    }
+
+    const digits = Array.from({length: 32}, digit);
+    digits[12] = '4';
+    digits[16] = '89ab'[Math.random() * 4 | 0];
+
+    return digits
+            .join('')
+            .match(/^(.{8})(.{4})(.{4})(.{4})(.{12})$/)!
+            .slice(1)
+            .join('-');
+}