anagram.js

function anagram(word) {
  var originalWord = wordObject(word);

  return {
    matches: function(wordArray) {
      if (typeof wordArray === 'string'){
        wordArray = Array.prototype.slice.call(arguments);
      }

      var wordMatches = [];
      for (var i = 0; i < wordArray.length; i++) {
        var wordMatcher = wordArray[i];
        if (word.length !== wordMatcher.length || word.toLowerCase() === wordMatcher.toLowerCase()) {
          continue;
        }
        var wordToCheck = wordObject(wordMatcher);
        if (checkWords(originalWord, wordToCheck)) {
          wordMatches.push(wordMatcher)
        }
      }
      return wordMatches;
    }
  };
}

function checkWords(word1, word2) {
  if (Object.keys(word1).length != Object.keys(word2).length) {
    return false;
  }
  for (len in word1) {
    if (!word1.hasOwnProperty(len)) {
      continue;
    }
    if (word1[len] !== word2[len]) {
      return false;
    }
  }
  return true;
}

function wordObject(word) {
  var charArray = word.split('');
  var charCount = {};
  for (i = 0; i < charArray.length; i++) {
    var char = charArray[i].toLowerCase();
    if (typeof charCount[char] === "number") {
      charCount[char]++;
    } else {
      charCount[char] = 1;
    }
  }
  return charCount;
}

module.exports = anagram;

anagram_test.spec.js

var anagram = require('./anagram');

describe('Anagram', function() {

  it("no matches",function() {
    var subject = new anagram("diaper");
    var matches = subject.matches([ "hello", "world", "zombies", "pants"]);

    expect(matches).toEqual([]);
  });

  it("detects simple anagram",function() {
    var subject = new anagram("ant");
    var matches = subject.matches(['tan', 'stand', 'at']);

    expect(matches).toEqual(['tan']);
  });

  it("does not detect false positives",function() {
    var subject = new anagram("galea");
    var matches = subject.matches(["eagle"]);

    expect(matches).toEqual([]);
  });

  it("detects multiple anagrams",function() {
    var subject = new anagram("master");
    var matches = subject.matches(['stream', 'pigeon', 'maters']);

    expect(matches).toEqual(['stream', 'maters']);
  });

  it("does not detect anagram subsets",function() {
    var subject = new anagram("good");
    var matches = subject.matches(['dog', 'goody']);

    expect(matches).toEqual([]);
  });

  it("detects anagram",function() {
    var subject = new anagram("listen");
    var matches = subject.matches(['enlists', 'google', 'inlets', 'banana']);

    expect(matches).toEqual(['inlets']);
  });

  it("detects multiple anagrams",function() {
    var subject = new anagram("allergy");
    var matches = subject.matches(['gallery', 'ballerina', 'regally', 'clergy', 'largely', 'leading']);

    expect(matches).toEqual(['gallery', 'regally', 'largely']);
  });

  it("detects anagrams case-insensitively",function() {
    var subject = new anagram("Orchestra");
    var matches = subject.matches(['cashregister', 'Carthorse', 'radishes']);

    expect(matches).toEqual(['Carthorse']);
  });

  it("does not detect a word as its own anagram",function() {
    var subject = new anagram("banana");
    var matches = subject.matches(['Banana']);

    expect(matches).toEqual([]);
  });

  it("matches() accepts string arguments",function() {
    var subject = new anagram("ant");
    var matches = subject.matches("stand", "tan", "at");

    expect(matches).toEqual(["tan"]);
  });

});