feat: palindrome algorithm

Author: francislagares

src/algorithms/palindromes/palindromes.ts

@@ -0,0 +1,11 @@
+export const palindrome = (str: string) => {
+  const reversed = str.split('').reverse().join('');
+
+  return str === reversed;
+};
+
+export const palindromeWithEvery = (str: string) => {
+  return str
+    .split('')
+    .every((character, index) => character === str[str.length - index - 1]);
+};

src/algorithms/palindromes/tests/palindromes.test.ts

@@ -0,0 +1,44 @@
+import { describe, test } from 'vitest';
+import { palindrome, palindromeWithEvery } from '../palindromes';
+
+describe('Palindromes', () => {
+  test('palindrome function is defined', () => {
+    expect(typeof palindrome).toEqual('function');
+    expect(typeof palindromeWithEvery).toEqual('function');
+  });
+
+  test('"aba" is a palindrome', () => {
+    expect(palindrome('aba')).toBeTruthy();
+    expect(palindromeWithEvery('aba')).toBeTruthy();
+  });
+
+  test('" aba" is not a palindrome', () => {
+    expect(palindrome(' aba')).toBeFalsy();
+    expect(palindromeWithEvery(' aba')).toBeFalsy();
+  });
+
+  test('"aba " is not a palindrome', () => {
+    expect(palindrome('aba ')).toBeFalsy();
+    expect(palindromeWithEvery('aba ')).toBeFalsy();
+  });
+
+  test('"greetings" is not a palindrome', () => {
+    expect(palindrome('greetings')).toBeFalsy();
+    expect(palindromeWithEvery('greetings')).toBeFalsy();
+  });
+
+  test('"1000000001" a palindrome', () => {
+    expect(palindrome('1000000001')).toBeTruthy();
+    expect(palindromeWithEvery('1000000001')).toBeTruthy();
+  });
+
+  test('"Fish hsif" is not a palindrome', () => {
+    expect(palindrome('Fish hsif')).toBeFalsy();
+    expect(palindromeWithEvery('Fish hsif')).toBeFalsy();
+  });
+
+  test('"pennep" a palindrome', () => {
+    expect(palindrome('pennep')).toBeTruthy();
+    expect(palindromeWithEvery('pennep')).toBeTruthy();
+  });
+});