Merge pull request #168 from sylvainpolletvillard/fix-array-at

fix ArraySchema#at with negative indexes
colyseus · Apr 5, 2024 · a1eb541 · a1eb541
2 parents 81932bc + d0e0502
commit a1eb541
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diff --git a/src/types/ArraySchema.ts b/src/types/ArraySchema.ts
@@ -167,6 +167,13 @@ export class ArraySchema<V = any> implements Array<V>, SchemaDecoderCallbacks {
         //
         // FIXME: this should be O(1)
         //
+
+	    index = Math.trunc(index) || 0;
+	    // Allow negative indexing from the end
+	    if (index < 0) index += this.length;
+	    // OOB access is guaranteed to return undefined
+	    if (index < 0 || index >= this.length) return undefined;
+
         const key = Array.from(this.$items.keys())[index];
         return this.$items.get(key);
     }

diff --git a/test/ArraySchema.test.ts b/test/ArraySchema.test.ts
@@ -1495,6 +1495,16 @@ describe("ArraySchema Tests", () => {
 
             assert.deepEqual([1,2,3], arr.toJSON());
         });
+
+        it("#at()", () => {
+            const arr = new ArraySchema<number>(1,2,3,4,5);
+            assert.strictEqual(1, arr.at(0));
+            assert.strictEqual(3, arr.at(2));
+            assert.strictEqual(5, arr.at(-1));
+            assert.strictEqual(1, arr.at(-5));
+            assert.strictEqual(undefined, arr.at(5));
+            assert.strictEqual(undefined, arr.at(-6));
+        });
     })
 
     describe("ArraySchema <-> Array type interchangability", () => {