Add Knuth shuffling (TypeScript).

TypeScript/src/math/prob/fisher_yates.tsx

@@ -0,0 +1,17 @@
+/** Shuffles a slice in place.
+ *
+ * @param {Array<T>} slice - Mutable slice to shuffle.
+ */
+export function shuffle_in_place<T>(slice: Array<T>): void {
+  // TypeScript doesn't have unsigned types. This can't underflow.
+  let i = slice.length - 1;
+
+  while (i > 0) {
+    // Crux of Knuth shuffling.
+    // Select a random index up to i, then swap the item at i with it
+    const j = Math.floor(Math.random() * i);
+    [slice[i], slice[j]] = [slice[j], slice[i]];
+
+    --i;
+  }
+}