Added 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 }