Implement exercise isbn-verifier

config.json

@@ -1119,6 +1119,19 @@
         "Pattern recognition",
         "Regular expressions"
       ]
+    },
+    {
+      "uuid": "213ea396-0c25-e480-4e76-5876975bdd54ac4890c",
+      "slug": "isbn-verifier",
+      "core": false,
+      "unlocked_by": "bob",
+      "difficulty": 4,
+      "topics": [
+        "control_flow_conditionals",
+        "control_flow_loops",
+        "pattern_recognition",
+        "regular_expressions"
+      ]
     }
   ],
   "foregone": []

exercises/isbn-verifier/README.md

@@ -0,0 +1,62 @@
+# ISBN Verifier
+
+Check if a given string is a valid ISBN-10 number.
+
+## Functionality
+
+Given an unknown string the program should check if the provided string is a valid ISBN-10.
+Putting this into place requires some thinking about preprocessing/parsing of the string prior to calculating the check digit for the ISBN.
+
+The program should allow for ISBN-10 without the separating dashes to be verified as well.
+
+## ISBN
+
+Let's take a random ISBN-10 number, say `3-598-21508-8` for this.
+The first digit block indicates the group where the ISBN belongs. Groups can consist of shared languages, geographic regions or countries. The leading '3' signals this ISBN is from a german speaking country.
+The following number block is to identify the publisher. Since this is a three digit publisher number there is a 5 digit title number for this book.
+The last digit in the ISBN is the check digit which is used to detect read errors.
+
+The first 9 digits in the ISBN have to be between 0 and 9.
+The check digit can additionally be an 'X' to allow 10 to be a valid check digit as well.
+
+A valid ISBN-10 is calculated with this formula `(x1 * 10 + x2 * 9 + x3 * 8 + x4 * 7 + x5 * 6 + x6 * 5 + x7 * 4 + x8 * 3 + x9 * 2 + x10 * 1) mod 11 == 0`
+So for our example ISBN this means:
+(3 * 10 + 5 * 9 + 9 * 8 + 8 * 7 + 2 * 6 + 1 * 5 + 5 * 4 + 0 * 3 + 8 * 2 + 8 * 1) mod 11 = 0
+
+Which proves that the ISBN is valid.
+
+## Setup
+
+Go through the setup instructions for ECMAScript to
+install the necessary dependencies:
+
+http://exercism.io/languages/ecmascript
+
+## 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
+
+Wikipedia [https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation](https://en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-10_check_digit_calculation)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

exercises/isbn-verifier/example.js

@@ -0,0 +1,17 @@
+export default class ISBN {
+
+  constructor(isbn) {
+    this.isbn = isbn.replace(/-/g, '');
+  }
+
+  isValid() {
+    if (!this.isbn.match(/^(\d{9}[\dxX])$/)) return false;
+
+    const digits = [...this.isbn];
+    if (digits[9].match(/[xX]/)) digits[9] = 10;
+
+    const sum = digits.reduce((acc, value, index) => acc + ((10 - index) * parseInt(value, 10)), 0);
+
+    return sum % 11 === 0;
+  }
+}

exercises/isbn-verifier/isbn-verifier.spec.js

@@ -0,0 +1,81 @@
+import ISBN from './isbn-verifier.js';
+
+describe('ISBN Verifier Test Suite', () => {
+  test('valid isbn number', () => {
+    const isbn = new ISBN('3-598-21508-8');
+
+    expect(isbn.isValid()).toEqual(true);
+  });
+
+  test('invalid isbn check digit', () => {
+    const isbn = new ISBN('3-598-21508-9');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('valid isbn number with a check digit of 10', () => {
+    const isbn = new ISBN('3-598-21507-X');
+
+    expect(isbn.isValid()).toEqual(true);
+  });
+
+  xtest('check digit is a character other than X', () => {
+    const isbn = new ISBN('3-598-21507-A');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('invalid character in isbn', () => {
+    const isbn = new ISBN('3-598-2K507-0');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('X is only valid as a check digit', () => {
+    const isbn = new ISBN('3-598-2X507-0');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('valid isbn without separating dashes', () => {
+    const isbn = new ISBN('3598215088');
+
+    expect(isbn.isValid()).toEqual(true);
+  });
+
+  xtest('isbn without separating dashes and X as check digit', () => {
+    const isbn = new ISBN('359821507X');
+
+    expect(isbn.isValid()).toEqual(true);
+  });
+
+  xtest('isbn without check digit and dashes', () => {
+    const isbn = new ISBN('359821507');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('too long isbn and no dashes', () => {
+    const isbn = new ISBN('3598215078X');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('isbn without check digit', () => {
+    const isbn = new ISBN('3-598-21507');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('too long isbn', () => {
+    const isbn = new ISBN('3-598-21507-XA');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+
+  xtest('check digit of X should not be used for 0', () => {
+    const isbn = new ISBN('3-598-21515-X');
+
+    expect(isbn.isValid()).toEqual(false);
+  });
+});

exercises/isbn-verifier/package.json

@@ -0,0 +1,69 @@
+{
+  "name": "xecmascript",
+  "version": "0.0.0",
+  "description": "Exercism exercises in ECMAScript 6.",
+  "author": "Katrina Owen",
+  "private": true,
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/exercism/xecmascript"
+  },
+  "devDependencies": {
+    "babel-jest": "^20.0.3",
+    "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": "^20.0.4"
+  },
+  "jest": {
+    "modulePathIgnorePatterns": [
+      "package.json"
+    ]
+  },
+  "babel": {
+    "presets": [
+      "env"
+    ],
+    "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": {}
+}