2016 Update

Task/Caesar-cipher/JavaScript/caesar-cipher-3.js

@@ -0,0 +1,43 @@
+((key, strPlain) => {
+
+    // Int -> String -> String
+    let caesar = (k, s) => s.split('')
+        .map(c => tr(
+            inRange(['a', 'z'], c) ? 'a' :
+            inRange(['A', 'Z'], c) ? 'A' : 0,
+            k, c
+        ))
+        .join('');
+
+    // Int -> String -> String
+    let unCaesar = (k, s) => caesar(26 - (k % 26), s);
+
+    // Char -> Int -> Char -> Char
+    let tr = (base, offset, char) =>
+        base ? (
+            String.fromCharCode(
+                ord(base) + (
+                    ord(char) - ord(base) + offset
+                ) % 26
+            )
+        ) : char;
+
+    // [a, a] -> a -> b
+    let inRange = ([min, max], v) => !(v < min || v > max);
+
+    // Char -> Int
+    let ord = c => c.charCodeAt(0);
+
+    // range :: Int -> Int -> [Int]
+    let range = (m, n) =>
+        Array.from({
+            length: Math.floor(n - m) + 1
+        }, (_, i) => m + i);
+
+    // TEST
+    let strCipher = caesar(key, strPlain),
+        strDecode = unCaesar(key, strCipher);
+
+    return [strCipher, ' -> ', strDecode];
+
+})(114, 'Curio, Cesare venne, e vide e vinse ? ');