fix(snippet): limit seed to 32bits according to splitmix32

objkt-com · May 24, 2024 · 649edc4 · 649edc4
1 parent f47279c
commit 649edc4
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/src/snippet.js b/src/snippet.js
@@ -16,7 +16,7 @@ if (query.has('seed')) {
       query
         .get('seed')
         .replace(/[^0-9a-f]/gi, 'f')
-        .padEnd(12, 'f'),
+        .padEnd(8, 'f'),
       16
     ) % Number.MAX_SAFE_INTEGER;
   query.set('seed', $o.seed.toString(16));

diff --git a/test/test.snippet.js b/test/test.snippet.js
@@ -64,6 +64,16 @@ describe('$o', () => {
       assert.equal($o.rnd(), 0.03844817215576768);
     });
 
+    it("splitmix32's seed is in [0, 2^32-1] and wraps", () => {
+      const { $o } = init();
+      $o.seed = 0;
+      $o.rnd(null);
+      assert.equal($o.rnd(), 0.8505931859835982);
+      $o.seed = 2 ** 32;
+      $o.rnd(null);
+      assert.equal($o.rnd(), 0.8505931859835982);
+    });
+
     it('can be reset by passing null', () => {
       const { $o } = init();
       $o.seed = 928173;