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rootulp's solution

to Food Chain in the JavaScript Track

Published at Jul 13 2018 · 0 comments
Instructions
Test suite
Solution

Note:

This solution was written on an old version of Exercism. The tests below might not correspond to the solution code, and the exercise may have changed since this code was written.

Generate the lyrics of the song 'I Know an Old Lady Who Swallowed a Fly'.

While you could copy/paste the lyrics, or read them from a file, this problem is much more interesting if you approach it algorithmically.

This is a cumulative song of unknown origin.

This is one of many common variants.

I know an old lady who swallowed a fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a spider.
It wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a bird.
How absurd to swallow a bird!
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a cat.
Imagine that, to swallow a cat!
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a dog.
What a hog, to swallow a dog!
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a goat.
Just opened her throat and swallowed a goat!
She swallowed the goat to catch the dog.
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a cow.
I don't know how she swallowed a cow!
She swallowed the cow to catch the goat.
She swallowed the goat to catch the dog.
She swallowed the dog to catch the cat.
She swallowed the cat to catch the bird.
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.
She swallowed the spider to catch the fly.
I don't know why she swallowed the fly. Perhaps she'll die.

I know an old lady who swallowed a horse.
She's dead, of course!

Setup

Go through the setup instructions for JavaScript to install the necessary dependencies:

http://exercism.io/languages/javascript/installation

Running the test suite

The provided test suite uses Jasmine. You can install it by opening a terminal window and running the following command:

npm install -g jasmine

Run the test suite from the exercise directory with:

jasmine food-chain.spec.js

In many test suites all but the first test have been marked "pending". Once you get a test passing, activate the next one by changing xit to it.

Source

Wikipedia http://en.wikipedia.org/wiki/There_Was_an_Old_Lady_Who_Swallowed_a_Fly

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

food-chain.spec.js

var FoodChain = require('./food-chain');

describe('Food Chain', function () {
  var song = new FoodChain();

  it('fly', function () {
    var expected = 'I know an old lady who swallowed a fly.\nI don\'t know why she swallowed the fly. Perhaps she\'ll die.\n';

    expect(song.verse(1)).toEqual(expected);
  });

  xit('spider', function () {
    var expected = 'I know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' + 'I don\'t know why she swallowed the fly. Perhaps she\'ll die.\n';

    expect(song.verse(2)).toEqual(expected);
  });

  xit('bird', function () {
    var expected = 'I know an old lady who swallowed a bird.\n' +
      'How absurd to swallow a bird!\n' +
      'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. Perhaps she\'ll die.\n';

    expect(song.verse(3)).toEqual(expected);
  });

  xit('cat', function () {
    var expected = 'I know an old lady who swallowed a cat.\n' +
      'Imagine that, to swallow a cat!\n' +
      'She swallowed the cat to catch the bird.\n' +
      'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. ' +
      'Perhaps she\'ll die.\n';

    expect(song.verse(4)).toEqual(expected);
  });

  xit('dog', function () {
    var expected = 'I know an old lady who swallowed a dog.\n' +
      'What a hog, to swallow a dog!\n' +
      'She swallowed the dog to catch the cat.\n' +
      'She swallowed the cat to catch the bird.\n' +
      'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. ' +
      'Perhaps she\'ll die.\n';

    expect(song.verse(5)).toEqual(expected);
  });

  xit('goat', function () {
    var expected = 'I know an old lady who swallowed a goat.\n' +
      'Just opened her throat and swallowed a goat!\n' +
      'She swallowed the goat to catch the dog.\n' +
      'She swallowed the dog to catch the cat.\n' +
      'She swallowed the cat to catch the bird.\n' +
      'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. ' +
      'Perhaps she\'ll die.\n';

    expect(song.verse(6)).toEqual(expected);
  });

  xit('cow', function () {
    var expected = 'I know an old lady who swallowed a cow.\n' +
      'I don\'t know how she swallowed a cow!\n' +
      'She swallowed the cow to catch the goat.\n' +
      'She swallowed the goat to catch the dog.\n' +
      'She swallowed the dog to catch the cat.\n' +
      'She swallowed the cat to catch the bird.\n' +
      'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. ' +
      'Perhaps she\'ll die.\n';

    expect(song.verse(7)).toEqual(expected);
  });

  xit('horse', function () {
    var expected = 'I know an old lady who swallowed a horse.\n' + 'She\'s dead, of course!\n';

    expect(song.verse(8)).toEqual(expected);
  });

  xit('multiple verses', function () {
    var expected = '';

    expected += 'I know an old lady who swallowed a fly.\nI don\'t know why she swallowed the fly. Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\n' +
      'She swallowed the spider to catch the fly.\n' +
      'I don\'t know why she swallowed the fly. Perhaps she\'ll die.\n\n';

    expect(song.verses(1, 2)).toEqual(expected);
  });

  xit('the whole song', function () {
    var expected = '';

    expected += 'I know an old lady who swallowed a fly.\nI don\'t know why she swallowed the fly. Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a spider.\nIt wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a bird.\n' +
    'How absurd to swallow a bird!\n' +
    'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a cat.\n' +
    'Imagine that, to swallow a cat!\n' +
    'She swallowed the cat to catch the bird.\n' +
    'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. ' +
    'Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a dog.\n' +
    'What a hog, to swallow a dog!\n' +
    'She swallowed the dog to catch the cat.\n' +
    'She swallowed the cat to catch the bird.\n' +
    'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. ' +
    'Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a goat.\n' +
    'Just opened her throat and swallowed a goat!\n' +
    'She swallowed the goat to catch the dog.\n' +
    'She swallowed the dog to catch the cat.\n' +
    'She swallowed the cat to catch the bird.\n' +
    'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. ' +
    'Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a cow.\n' +
    'I don\'t know how she swallowed a cow!\n' +
    'She swallowed the cow to catch the goat.\n' +
    'She swallowed the goat to catch the dog.\n' +
    'She swallowed the dog to catch the cat.\n' +
    'She swallowed the cat to catch the bird.\n' +
    'She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n' +
    'She swallowed the spider to catch the fly.\n' +
    'I don\'t know why she swallowed the fly. ' +
    'Perhaps she\'ll die.\n\n';
    expected += 'I know an old lady who swallowed a horse.\n' + 'She\'s dead, of course!\n\n';

    expect(song.verses(1, 8)).toEqual(expected);
  });
});
// Copy solution from:
// https://github.com/breethomas/exercisms/blob/master/javascript/food-chain/food-chain.js

var Song = function(lyrics) {
  this.verseArray = lyrics.split('\n\n');
}

Song.prototype.verse = function(start) {
  return this.verseArray[start - 1] + '\n';
}

Song.prototype.verses = function(start, end) {
  var sliced = this.verseArray.slice(start - 1, end);
  return sliced.join('\n\n') + '\n\n';
}

Song.prototype.sing = function() {
  var end = this.verseArray.length;
  return this.verses(1, end);
}

Song.oldLadyTune = function() {
  return new Song(oldLadyTune);
}

var oldLadyTune = "\
I know an old lady who swallowed a fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a spider.\n\
It wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a bird.\n\
How absurd to swallow a bird!\n\
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a cat.\n\
Imagine that, to swallow a cat!\n\
She swallowed the cat to catch the bird.\n\
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a dog.\n\
What a hog, to swallow a dog!\n\
She swallowed the dog to catch the cat.\n\
She swallowed the cat to catch the bird.\n\
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a goat.\n\
Just opened her throat and swallowed a goat!\n\
She swallowed the goat to catch the dog.\n\
She swallowed the dog to catch the cat.\n\
She swallowed the cat to catch the bird.\n\
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a cow.\n\
I don't know how she swallowed a cow!\n\
She swallowed the cow to catch the goat.\n\
She swallowed the goat to catch the dog.\n\
She swallowed the dog to catch the cat.\n\
She swallowed the cat to catch the bird.\n\
She swallowed the bird to catch the spider that wriggled and jiggled and tickled inside her.\n\
She swallowed the spider to catch the fly.\n\
I don't know why she swallowed the fly. Perhaps she'll die.\n\
\n\
I know an old lady who swallowed a horse.\n\
She's dead, of course!";

module.exports = Song.oldLadyTune();

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