Function to get the closest country population to a given number

closest-country-population.js

const populations = {
  'China': 1439323776,
  'India': 1380004385,
  'United States': 331002651,
  'Indonesia': 273523615,
  'Pakistan': 220892340,
  'Brazil': 212559417,
  'Nigeria': 206139589,
  'Bangladesh': 164689383,
  'Russia': 145934462,
  'Mexico': 128932753,
  'Japan': 126476461,
  'Ethiopia': 114963588,
  'Philippines': 109581078,
  'Egypt': 102334404,
  'Vietnam': 97338579,
  'DR Congo': 89561403,
  'Turkey': 84339067,
  'Iran': 83992949,
  'Germany': 83783942,
  'Thailand': 69799978,
  'United Kingdom': 67886011,
  'France': 65273511,
  'Italy': 60461826,
  'Tanzania': 59734218,
  'South Africa': 59308690,
  'Myanmar': 54409800,
  'Kenya': 53771296,
  'South Korea': 51269185,
  'Colombia': 50882891,
  'Spain': 46754778,
  'Uganda': 45741007,
  'Argentina': 45195774,
  'Algeria': 43851044,
  'Sudan': 43849260,
  'Ukraine': 43733762,
  'Iraq': 40222493,
  'Afghanistan': 38928346,
  'Poland': 37846611,
  'Canada': 37742154,
  'Morocco': 36910560,
  'Saudi Arabia': 34813871,
  'Uzbekistan': 33469203,
  'Peru': 32971854,
  'Angola': 32866272,
  'Malaysia': 32365999,
  'Mozambique': 31255435,
  'Ghana': 31072940,
  'Yemen': 29825964,
  'Nepal': 29136808,
  'Venezuela': 28435940,
  'Madagascar': 27691018,
  'Cameroon': 26545863,
  'Côte d\'Ivoire': 26378274,
  'North Korea': 25778816,
  'Australia': 25499884,
  'Niger': 24206644,
  'Taiwan': 23816775,
  'Sri Lanka': 21413249,
  'Burkina Faso': 20903273,
  'Mali': 20250833,
  'Romania': 19237691,
  'Malawi': 19129952,
  'Chile': 19116201,
  'Kazakhstan': 18776707,
  'Zambia': 18383955,
  'Guatemala': 17915568,
  'Ecuador': 17643054,
  'Syria': 17500658,
  'Netherlands': 17134872,
  'Senegal': 16743927,
  'Cambodia': 16718965,
  'Chad': 16425864,
  'Somalia': 15893222,
  'Zimbabwe': 14862924,
  'Guinea': 13132795,
  'Rwanda': 12952218,
  'Benin': 12123200,
  'Burundi': 11890784,
  'Tunisia': 11818619,
  'Bolivia': 11673021,
  'Belgium': 11589623,
  'Haiti': 11402528,
  'Cuba': 11326616,
  'South Sudan': 11193725,
  'Dominican Republic': 10847910,
  'Czech Republic (Czechia)': 10708981,
  'Greece': 10423054,
  'Jordan': 10203134,
  'Portugal': 10196709,
  'Azerbaijan': 10139177,
  'Sweden': 10099265,
  'Honduras': 9904607,
  'United Arab Emirates': 9890402,
  'Hungary': 9660351,
  'Tajikistan': 9537645,
  'Belarus': 9449323,
  'Austria': 9006398,
  'Papua New Guinea': 8947024,
  'Serbia': 8737371,
  'Israel': 8655535,
  'Switzerland': 8654622,
  'Togo': 8278724,
  'Sierra Leone': 7976983,
  'Hong Kong': 7496981,
  'Laos': 7275560,
  'Paraguay': 7132538,
  'Bulgaria': 6948445,
  'Libya': 6871292,
  'Lebanon': 6825445,
  'Nicaragua': 6624554,
  'Kyrgyzstan': 6524195,
  'El Salvador': 6486205,
  'Turkmenistan': 6031200,
  'Singapore': 5850342,
  'Denmark': 5792202,
  'Finland': 5540720,
  'Congo': 5518087,
  'Slovakia': 5459642,
  'Norway': 5421241,
  'Oman': 5106626,
  'State of Palestine': 5101414,
  'Costa Rica': 5094118,
  'Liberia': 5057681,
  'Ireland': 4937786,
  'Central African Republic': 4829767,
  'New Zealand': 4822233,
  'Mauritania': 4649658,
  'Panama': 4314767,
  'Kuwait': 4270571,
  'Croatia': 4105267,
  'Moldova': 4033963,
  'Georgia': 3989167,
  'Eritrea': 3546421,
  'Uruguay': 3473730,
  'Bosnia and Herzegovina': 3280819,
  'Mongolia': 3278290,
  'Armenia': 2963243,
  'Jamaica': 2961167,
  'Qatar': 2881053,
  'Albania': 2877797,
  'Puerto Rico': 2860853,
  'Lithuania': 2722289,
  'Namibia': 2540905,
  'Gambia': 2416668,
  'Botswana': 2351627,
  'Gabon': 2225734,
  'Lesotho': 2142249,
  'North Macedonia': 2083374,
  'Slovenia': 2078938,
  'Guinea-Bissau': 1968001,
  'Latvia': 1886198,
  'Bahrain': 1701575,
  'Equatorial Guinea': 1402985,
  'Trinidad and Tobago': 1399488,
  'Estonia': 1326535,
  'Timor-Leste': 1318445,
  'Mauritius': 1271768,
  'Cyprus': 1207359,
  'Eswatini': 1160164,
  // Countries with population < 1 million have been removed
};

const getClosest = (userCount) => {
  const countriesWithPopulation = Object.entries(populations);

  let i = 0;
  let count = countriesWithPopulation[i][1];

  while (userCount < count && i < countriesWithPopulation.length - 1) {
    count = countriesWithPopulation[i++][1];
  }

  if (i === 0) {
    return countriesWithPopulation[i][0];
  }

  const [nextCountry, nextCountryPop] = countriesWithPopulation[i - 1];
  const [prevCountry, prevCountryPop] = countriesWithPopulation[i];

  const differenceToNextCountry = Math.abs(userCount - nextCountryPop);
  const differenceToPrevCountry = Math.abs(userCount - prevCountryPop);

  if (differenceToNextCountry <= differenceToPrevCountry) {
    return nextCountry;
  }
  return prevCountry;
};

console.log(getClosest(6495231));