freeCodeCamp/curriculum/challenges/english/10-coding-interview-prep/rosetta-code/day-of-the-week.md

title	id	challengeType	forumTopicId
Day of the week	5966f99c45e8976909a85575	5	302245

Description

A company decides that whenever Xmas falls on a Sunday they will give their workers all extra paid holidays so that, together with any public holidays, workers will not have to work the following week (between the 25th of December and the first of January).

Instructions

Write a function that takes a start year and an end year and return an array of all the years where the 25th of December will be a Sunday.

Tests

tests:
  - text: <code>findXmasSunday</code> should be a function.
    testString: assert(typeof findXmasSunday === 'function');
  - text: <code>findXmasSunday(2000, 2100)</code> should return an array.
    testString: assert(typeof findXmasSunday(2000, 2100) === 'object');
  - text: <code>findXmasSunday(1970, 2017)</code> should return <code>[1977, 1983, 1988, 1994, 2005, 2011, 2016]</code>
    testString: assert.deepEqual(findXmasSunday(1970, 2017), firstSolution);
  - text: <code>findXmasSunday(2008, 2121)</code> should return <code>[2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118]</code>
    testString: assert.deepEqual(findXmasSunday(2008, 2121), secondSolution);

Challenge Seed

function findXmasSunday(start, end) {

  return true;
}

After Test

const firstSolution = [1977, 1983, 1988, 1994, 2005, 2011, 2016];
const secondSolution = [2011, 2016, 2022, 2033, 2039, 2044, 2050, 2061, 2067, 2072, 2078, 2089, 2095, 2101, 2107, 2112, 2118];

Solution

function findXmasSunday(start, end) {
  const xmasSunday = [];
  for (let year = start; year <= end; year++) {
    const xmas = new Date(year, 11, 25);
    if (xmas.getDay() === 0) {
      xmasSunday.push(year);
    }
  }
  return xmasSunday;
}