diff --git a/src/utils.tsx b/src/utils.tsx
index 0ede4ea..0e06877 100644
--- a/src/utils.tsx
+++ b/src/utils.tsx
@@ -105,6 +105,19 @@ export function unique<T>(array: T[]): T[] {
   return [...new Set(array)]
 }
 
+// shuffle a copy of an array
+export function shuffle<T>(arr: readonly T[]): T[] {
+  const out = arr.slice()
+  for (let i = out.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1))
+
+    const tmp = out[i]!
+    out[i] = out[j]!
+    out[j] = tmp
+  }
+  return out
+}
+
 // random number between 1 and 10, with decreasing probability
 export function weightedRand(): number {
   // Weights: 1 has weight 10, 2 has weight 9, ..., 10 has weight 1