feat: add isPangram algorithm

String/IsPangram.js

@@ -0,0 +1,25 @@
+/**
+ * @function isPangram
+ * @description A pangram is a sentence that contains every letter of
+ *   the alphabet at least once. This function checks whether a given
+ *   string is a pangram, ignoring case.
+ * @param {string} str - The input string
+ * @returns {boolean} - True if the string is a pangram, false otherwise
+ * @see https://en.wikipedia.org/wiki/Pangram
+ * @example isPangram("The quick brown fox jumps over the lazy dog") => true
+ * @example isPangram("Hello World") => false
+ */
+const isPangram = (str) => {
+  if (typeof str !== 'string') {
+    throw new TypeError('Input must be a string')
+  }
+  const letters = new Set(
+    str
+      .toLowerCase()
+      .replace(/[^a-z]/g, '')
+      .split('')
+  )
+  return letters.size === 26
+}
+
+export { isPangram }

String/test/IsPangram.test.js

@@ -0,0 +1,37 @@
+import { isPangram } from '../IsPangram.js'
+
+describe('isPangram', () => {
+  test("'The quick brown fox jumps over the lazy dog' is a pangram", () => {
+    expect(isPangram('The quick brown fox jumps over the lazy dog')).toBe(true)
+  })
+
+  test("'Hello World' is NOT a pangram", () => {
+    expect(isPangram('Hello World')).toBe(false)
+  })
+
+  test('empty string is NOT a pangram', () => {
+    expect(isPangram('')).toBe(false)
+  })
+
+  test('case insensitive check', () => {
+    expect(isPangram('THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG')).toBe(true)
+  })
+
+  test('string with numbers and symbols but all letters is a pangram', () => {
+    expect(isPangram('1 The quick brown fox jumps over the lazy dog 2!')).toBe(
+      true
+    )
+  })
+
+  test('string missing one letter is NOT a pangram', () => {
+    expect(isPangram('The quick brown fox jumps over the lazy cat')).toBe(false)
+  })
+
+  test('throws TypeError for non-string input', () => {
+    expect(() => isPangram(123)).toThrow(TypeError)
+  })
+
+  test('throws TypeError for null input', () => {
+    expect(() => isPangram(null)).toThrow(TypeError)
+  })
+})