PatrickMcSweeny's solution to Word Count on the JavaScript track

Instructions

Test suite

Solution

Note:

This exercise has changed since this solution was written.

Given a phrase, count the occurrences of each word in that phrase.

For example for the input "olly olly in come free"

olly: 2
in: 1
come: 1
free: 1

Setup

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

https://exercism.io/tracks/javascript/installation

Requirements

Install assignment dependencies:

$ npm install

Making the test suite pass

Execute the tests with:

$ 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

This is a classic toy problem, but we were reminded of it by seeing it in the Go Tour.

Submitting Incomplete Solutions

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

word-count.spec.js

import { Words } from './word-count';

describe('words()', () => {
  const words = new Words();

  test('counts one word', () => {
    const expectedCounts = { word: 1 };
    expect(words.count('word')).toEqual(expectedCounts);
  });

  xtest('counts one of each', () => {
    const expectedCounts = { one: 1, of: 1, each: 1 };
    expect(words.count('one of each')).toEqual(expectedCounts);
  });

  xtest('counts multiple occurrences', () => {
    const expectedCounts = {
      one: 1, fish: 4, two: 1, red: 1, blue: 1,
    };
    expect(words.count('one fish two fish red fish blue fish')).toEqual(expectedCounts);
  });

  xtest('includes punctuation', () => {
    const expectedCounts = {
      car: 1, ':': 2, carpet: 1, as: 1, java: 1, 'javascript!!&@$%^&': 1,
    };
    expect(words.count('car : carpet as java : javascript!!&@$%^&')).toEqual(expectedCounts);
  });

  xtest('includes numbers', () => {
    const expectedCounts = { testing: 2, 1: 1, 2: 1 };
    expect(words.count('testing 1 2 testing')).toEqual(expectedCounts);
  });

  xtest('normalizes to lower case', () => {
    const expectedCounts = { go: 3 };
    expect(words.count('go Go GO')).toEqual(expectedCounts);
  });

  xtest('counts properly international characters', () => {
    const expectedCounts = {
      '¡hola!': 1, '¿qué': 1, 'tal?': 1, 'привет!': 1,
    };
    expect(words.count('¡Hola! ¿Qué tal? Привет!')).toEqual(expectedCounts);
  });

  xtest('counts multiline', () => {
    const expectedCounts = { hello: 1, world: 1 };
    expect(words.count('hello\nworld')).toEqual(expectedCounts);
  });

  xtest('counts tabs', () => {
    const expectedCounts = { hello: 1, world: 1 };
    expect(words.count('hello\tworld')).toEqual(expectedCounts);
  });

  xtest('counts multiple spaces as one', () => {
    const expectedCounts = { hello: 1, world: 1 };
    expect(words.count('hello  world')).toEqual(expectedCounts);
  });

  xtest('does not count leading or trailing whitespace', () => {
    const expectedCounts = { introductory: 1, course: 1 };
    expect(words.count('\t\tIntroductory Course      ')).toEqual(expectedCounts);
  });

  xtest('handles properties that exist on Object’s prototype', () => {
    const expectedCounts = {
      reserved: 1, words: 1, like: 1, constructor: 1, and: 1, tostring: 1, 'ok?': 1,
    };
    expect(words.count('reserved words like constructor and toString ok?')).toEqual(expectedCounts);
  });
});

export class Words {
  count(inputString) {
    let counts = {};
    let words = inputString
      .toLowerCase()
      .trim()
      .split(/\s+/);

    words.forEach(function(word) {
      counts[word] = words.filter(wordMatch => word === wordMatch).length;
    });

    return counts;
  }
}

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PatrickMcSweeny's solution

to Word Count in the JavaScript Track