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packages/cli/src/utils/array/index.test.ts

@@ -0,0 +1,24 @@
+import { findDuplicates } from "@utils/array";
+
+test("Find duplicates from array", () => {
+    const testCases = [
+        {
+            input: [],
+            output: [],
+        },
+
+        {
+            input: [1, 2, 3, 3, "3", "3"],
+            output: [3, "3"],
+        },
+        {
+            input: [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5],
+            output: [1, 2, 3, 4, 5],
+        },
+    ];
+
+    testCases.forEach((testCase) => {
+        const result = findDuplicates(testCase.input);
+        expect(result).toEqual(testCase.output);
+    });
+});

packages/cli/src/utils/array/index.ts

@@ -0,0 +1,5 @@
+export const findDuplicates = (arr: (string | number)[]) => {
+    const duplicates = arr.filter((item, index) => arr.indexOf(item) !== index);
+    const unique = new Set(duplicates);
+    return Array.from(unique);
+};