Merge branch 'solutions' into master

caesar/caesar.js

@@ -1,5 +1,26 @@
-const caesar = function() {
+const caesar = function(string, shift) {
+  return string
+    .split("")
+    .map(char => shiftChar(char, shift))
+    .join("");
+};
 
-}
+const codeSet = code => (code < 97 ? 65 : 97);
 
-module.exports = caesar
+// this function is just a fancy way of doing % so that it works with negative numbers
+// see this link for details:
+// https://stackoverflow.com/questions/4467539/javascript-modulo-gives-a-negative-result-for-negative-numbers
+const mod = (n, m) => (n % m + m) % m;
+
+const shiftChar = (char, shift) => {
+  const code = char.charCodeAt();
+
+  if ((code >= 65 && code <= 90) || (code >= 97 && code <= 122)) {
+    return String.fromCharCode(
+      mod(code + shift - codeSet(code), 26) + codeSet(code)
+    );
+  }
+  return char;
+};
+
+module.exports = caesar;

caesar/caesar.spec.js

@@ -1,23 +1,23 @@
-const caesar = require('./caesar')
+const caesar = require("./caesar");
 
-describe('caesar', function() {
-  it('works with single letters', function() {
-    expect(caesar('A', 1)).toEqual('B');
+describe("caesar", () => {
+  it("works with single letters", () => {
+    expect(caesar("A", 1)).toEqual("B");
   });
-  xit('works with words', function() {
-    expect(caesar('Aaa', 1)).toEqual('Bbb');
+  it("works with words", () => {
+    expect(caesar("Aaa", 1)).toEqual("Bbb");
   });
-  xit('works with phrases', function() {
-    expect(caesar('Hello, World!', 5)).toEqual('Mjqqt, Btwqi!');
+  it("works with phrases", () => {
+    expect(caesar("Hello, World!", 5)).toEqual("Mjqqt, Btwqi!");
   });
-  xit('works with negative shift', function() {
-    expect(caesar('Mjqqt, Btwqi!', -5)).toEqual('Hello, World!');
+  it("works with negative shift", () => {
+    expect(caesar("Mjqqt, Btwqi!", -5)).toEqual("Hello, World!");
   });
-  xit('wraps', function() {
-    expect(caesar('Z', 1)).toEqual('A');
+  it("wraps", () => {
+    expect(caesar("Z", 1)).toEqual("A");
   });
-  xit('works with large shift factors', function() {
-    expect(caesar('Hello, World!', 75)).toEqual('Ebiil, Tloia!');
+  it("works with large shift factors", () => {
+    expect(caesar("Hello, World!", 75)).toEqual("Ebiil, Tloia!");
   });
   xit('works with large negative shift factors', function() {
     expect(caesar('Hello, World!', -29)).toEqual('Ebiil, Tloia!');