pangram.js

function getAlphabet() {
  return 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'.split('');
}

function hasLetterFn(str) {
  str = str.toUpperCase();

  return function (isPangram, letter) {
    return isPangram && (str.indexOf(letter) > -1);
  }
}

function isPanagram(str) {
  return getAlphabet().reduce(hasLetterFn(str), true);
}

function countLettersFn(str) {
  var strLetters = str.toUpperCase().split('');

  return function (instances, letter) {
    instances[letter] = 0;

    strLetters.forEach(function (strLetter) {
      if (strLetter == letter) {
        instances[letter]++;
      }
    });

    return instances;
  }
}

function inspectPanagram(str) {
  var instances = getAlphabet().reduce(countLettersFn(str), {});

  for (key in instances) {
    instances[key.toLowerCase()] = instances[key];
  };

  instances.count = function (letter) {
    return instances[letter];
  };

  return instances;
}

pangram_spec.js

describe('isPanagram', function () {
  it('should return true for "Crazy Fredrick bought many very exquisite opal jewels"', function () {
    expect(isPanagram("Crazy Fredrick bought many very exquisite opal jewels")).toBe(true);
  });

  it('should return false for "A sentence that probably does not have every character"', function () {
    expect(isPanagram("A sentence that probably does not have every character")).toBe(false);
  });
});

describe('inspectPangram', function () {
  it('should return a hash containing A=2 for "Arse Face"', function () {
    expect(inspectPanagram("Arse Face").a).toBe(2);
  });

  it('should return a hash containing B=1 for "Bum Face"', function () {
    console.log(inspectPanagram("Bum Face"));
    expect(inspectPanagram("Bum Face").b).toBe(1);
  });

  it('should return a hash containing b=3 for "Bumblebee Face"', function () {
    var inspection = inspectPanagram("Bumblebee Face");
    expect(inspection.b).toBe(3);
    expect(inspection.B).toBe(3);
  });

  describe('inspect panagram hash', function () {
    it('should return b=3 via count method', function () {
      var inspection = inspectPanagram("Bumblebee Face");
      expect(inspection.count('b')).toBe(3);
      expect(inspection.count('B')).toBe(3);
    });

  });
});