Add check pangram algorithm

String/CheckPangram.js

@@ -0,0 +1,22 @@
+/*
+  Pangram is a sentence that contains all the letters in the alphabet
+  https://en.wikipedia.org/wiki/Pangram
+ */
+
+const checkPangram = (string) => {
+  if (typeof string !== 'string') {
+    throw new TypeError('The given value is not a string')
+  }
+
+  const frequency = new Set()
+
+  for (const letter of string.toLowerCase()) {
+    if (letter >= 'a' && letter <= 'z') {
+      frequency.add(letter)
+    }
+  }
+
+  return frequency.size === 26
+}
+
+export { checkPangram }

String/test/CheckPangram.test.js

@@ -0,0 +1,33 @@
+import { checkPangram } from '../CheckPangram'
+
+describe('checkPangram', () => {
+  it('"The quick brown fox jumps over the lazy dog" is a pangram', () => {
+    expect(
+      checkPangram('The quick brown fox jumps over the lazy dog')
+    ).toBeTruthy()
+  })
+
+  it('"Waltz, bad nymph, for quick jigs vex." is a pangram', () => {
+    expect(checkPangram('Waltz, bad nymph, for quick jigs vex.')).toBeTruthy()
+  })
+
+  it('"Jived fox nymph grabs quick waltz." is a pangram', () => {
+    expect(checkPangram('Jived fox nymph grabs quick waltz.')).toBeTruthy()
+  })
+
+  it('"My name is Unknown" is NOT a pangram', () => {
+    expect(checkPangram('My name is Unknown')).toBeFalsy()
+  })
+
+  it('"The quick brown fox jumps over the la_y dog" is NOT a pangram', () => {
+    expect(
+      checkPangram('The quick brown fox jumps over the la_y dog')
+    ).toBeFalsy()
+  })
+
+  it('Throws an error if given param is not a string', () => {
+    expect(() => {
+      checkPangram(undefined)
+    }).toThrow('The given value is not a string')
+  })
+})