javascript - roman-numerals

javascript/roman-numerals/README.md

@@ -0,0 +1,79 @@
+# Roman Numerals
+
+Write a function to convert from normal numbers to Roman Numerals.
+
+The Romans were a clever bunch. They conquered most of Europe and ruled
+it for hundreds of years. They invented concrete and straight roads and
+even bikinis. One thing they never discovered though was the number
+zero. This made writing and dating extensive histories of their exploits
+slightly more challenging, but the system of numbers they came up with
+is still in use today. For example the BBC uses Roman numerals to date
+their programmes.
+
+The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice
+these letters have lots of straight lines and are hence easy to hack
+into stone tablets).
+
+```text
+ 1  => I
+10  => X
+ 7  => VII
+```
+
+There is no need to be able to convert numbers larger than about 3000.
+(The Romans themselves didn't tend to go any higher)
+
+Wikipedia says: Modern Roman numerals ... are written by expressing each
+digit separately starting with the left most digit and skipping any
+digit with a value of zero.
+
+To see this in practice, consider the example of 1990.
+
+In Roman numerals 1990 is MCMXC:
+
+1000=M
+900=CM
+90=XC
+
+2008 is written as MMVIII:
+
+2000=MM
+8=VIII
+
+See also: http://www.novaroma.org/via_romana/numbers.html
+
+## Setup
+
+Go through the setup instructions for Javascript to
+install the necessary dependencies:
+
+[https://exercism.io/tracks/javascript/installation](https://exercism.io/tracks/javascript/installation)
+
+## Requirements
+
+Install assignment dependencies:
+
+```bash
+$ npm install
+```
+
+## Making the test suite pass
+
+Execute the tests with:
+
+```bash
+$ npm test
+```
+
+In the test suites all tests but the first have been skipped.
+
+Once you get a test passing, you can enable the next one by
+changing `xtest` to `test`.
+
+
+## Source
+
+The Roman Numeral Kata [http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals](http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

javascript/roman-numerals/package.json

@@ -0,0 +1,80 @@
+{
+  "name": "exercism-javascript",
+  "version": "0.0.0",
+  "description": "Exercism exercises in Javascript.",
+  "author": "Katrina Owen",
+  "private": true,
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/exercism/javascript"
+  },
+  "devDependencies": {
+    "babel-jest": "^21.2.0",
+    "babel-plugin-transform-builtin-extend": "^1.1.2",
+    "babel-preset-env": "^1.4.0",
+    "eslint": "^3.19.0",
+    "eslint-config-airbnb": "^15.0.1",
+    "eslint-plugin-import": "^2.2.0",
+    "eslint-plugin-jsx-a11y": "^5.0.1",
+    "eslint-plugin-react": "^7.0.1",
+    "jest": "^21.2.1"
+  },
+  "jest": {
+    "modulePathIgnorePatterns": [
+      "package.json"
+    ]
+  },
+  "babel": {
+    "presets": [
+      [
+        "env",
+        {
+          "targets": [
+            {
+              "node": "current"
+            }
+          ]
+        }
+      ]
+    ],
+    "plugins": [
+      [
+        "babel-plugin-transform-builtin-extend",
+        {
+          "globals": [
+            "Error"
+          ]
+        }
+      ],
+      [
+        "transform-regenerator"
+      ]
+    ]
+  },
+  "scripts": {
+    "test": "jest --no-cache ./*",
+    "watch": "jest --no-cache --watch ./*",
+    "lint": "eslint .",
+    "lint-test": "eslint . && jest --no-cache ./* "
+  },
+  "eslintConfig": {
+    "parserOptions": {
+      "ecmaVersion": 6,
+      "sourceType": "module"
+    },
+    "env": {
+      "es6": true,
+      "node": true,
+      "jest": true
+    },
+    "extends": "airbnb",
+    "rules": {
+      "import/no-unresolved": "off",
+      "import/extensions": "off"
+    }
+  },
+  "licenses": [
+    "MIT"
+  ],
+  "dependencies": {}
+}

javascript/roman-numerals/roman-numerals.js

@@ -0,0 +1,15 @@
+const toRoman = function (number) {
+  const numerals = { M: 1000, CM: 900, D: 500, CD: 400, C: 100, XC: 90, L: 50, XL: 40, X: 10, IX: 9, V: 5, IV: 4, I: 1 };
+
+  let roman = '';
+  for (const n in numerals) {
+    const value = Math.floor(number / numerals[n]);
+    if (value > 0) {
+      roman += n.repeat(value);
+      number -= (value * numerals[n]);
+    }
+  }
+  return roman;
+};
+
+export default toRoman;

javascript/roman-numerals/roman-numerals.spec.js

@@ -0,0 +1,22 @@
+import toRoman from './roman-numerals';
+
+describe('toRoman()', () => {
+  test('converts 1', () => expect(toRoman(1)).toEqual('I'));
+  test('converts 2', () => expect(toRoman(2)).toEqual('II'));
+  test('converts 3', () => expect(toRoman(3)).toEqual('III'));
+  test('converts 4', () => expect(toRoman(4)).toEqual('IV'));
+  test('converts 5', () => expect(toRoman(5)).toEqual('V'));
+  test('converts 6', () => expect(toRoman(6)).toEqual('VI'));
+  test('converts 9', () => expect(toRoman(9)).toEqual('IX'));
+  test('converts 27', () => expect(toRoman(27)).toEqual('XXVII'));
+  test('converts 48', () => expect(toRoman(48)).toEqual('XLVIII'));
+  test('converts 59', () => expect(toRoman(59)).toEqual('LIX'));
+  test('converts 93', () => expect(toRoman(93)).toEqual('XCIII'));
+  test('converts 141', () => expect(toRoman(141)).toEqual('CXLI'));
+  test('converts 163', () => expect(toRoman(163)).toEqual('CLXIII'));
+  test('converts 402', () => expect(toRoman(402)).toEqual('CDII'));
+  test('converts 575', () => expect(toRoman(575)).toEqual('DLXXV'));
+  test('converts 911', () => expect(toRoman(911)).toEqual('CMXI'));
+  test('converts 1024', () => expect(toRoman(1024)).toEqual('MXXIV'));
+  test('converts 3000', () => expect(toRoman(3000)).toEqual('MMM'));
+});