From 759d418d888c3fc2e116f2f4de404248ebb428af Mon Sep 17 00:00:00 2001
From: robonen <robonenandrew@gmail.com>
Date: Thu, 24 Oct 2024 07:28:15 +0700
Subject: [PATCH] feat(packages/stdlib): add last arrays util

---
 packages/stdlib/src/arrays/last/index.test.ts | 23 +++++++++++++++++++
 packages/stdlib/src/arrays/last/index.ts      | 20 ++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 packages/stdlib/src/arrays/last/index.test.ts
 create mode 100644 packages/stdlib/src/arrays/last/index.ts

diff --git a/packages/stdlib/src/arrays/last/index.test.ts b/packages/stdlib/src/arrays/last/index.test.ts
new file mode 100644
index 0000000..9f9ce60
--- /dev/null
+++ b/packages/stdlib/src/arrays/last/index.test.ts
@@ -0,0 +1,23 @@
+import { describe, it, expect } from 'vitest';
+import { last } from '.';
+
+describe('last', () => {
+  it('return the last element of a non-empty array', () => {
+    expect(last([1, 2, 3, 4, 5])).toBe(5);
+    expect(last(['a', 'b', 'c'])).toBe('c');
+  });
+
+  it('return undefined if the array is empty and no default value is provided', () => {
+    expect(last([])).toBeUndefined();
+  });
+
+  it('return the default value for an empty array with a default value', () => {
+    expect(last([], 42)).toBe(42);
+    expect(last([], 'default')).toBe('default');
+  });
+
+  it('return the first element even if a default value is provided', () => {
+    expect(last([1, 2, 3], 42)).toBe(3);
+    expect(last(['a', 'b', 'c'], 'default')).toBe('c');
+  });
+});
\ No newline at end of file
diff --git a/packages/stdlib/src/arrays/last/index.ts b/packages/stdlib/src/arrays/last/index.ts
new file mode 100644
index 0000000..4661aaf
--- /dev/null
+++ b/packages/stdlib/src/arrays/last/index.ts
@@ -0,0 +1,20 @@
+/**
+ * @name last
+ * @section Arrays
+ * @description Gets the last element of an array
+ * 
+ * @param {Value[]} arr The array to get the last element of
+ * @param {Value} [defaultValue] The default value to return if the array is empty
+ * @returns {Value | undefined} The last element of the array, or the default value if the array is empty
+ * 
+ * @example
+ * last([1, 2, 3, 4, 5]); // => 5
+ * 
+ * @example
+ * last([], 3); // => 3
+ * 
+ * @since 0.0.3
+ */
+export function last<Value>(arr: Value[], defaultValue?: Value) {
+  return arr[arr.length - 1] ?? defaultValue;
+}