Group options in select tag using JavaScript

Question

I want to group the countries by continents in JavaScript... assign multiple values from the select tag to an object in JavaScript if a country is selected from a particular continent it will have a particular score when the form is submitted e.g. countries from Europe 50 points ,Asia 40 points etc. so i want to group the countries by continents and use if else statements to give scores

<!--the select tag is inside a form >


    <select id="select-country" name="country" >
    <option value="" selected="">Select country</option>
    <option value="afghanistan">Afghanistan</option>
    <option value="albania">Albania</option>
    <option value="algeria">Algeria</option>
    <option value="angola">Angola</option>
    <option value="anguilla">Anguilla</option>
    <option value="antigua-and-barbuda">Antigua and Barbuda</option>
    <option value="argentina">Argentina</option>
    <option value="armenia">Armenia</option>
    <option value="australia">Australia</option>
    <option value="azerbaijan">Azerbaijan</option>
    <option value="bahamas">Bahamas</option>
    <option value="bangladesh">Bangladesh</option>
    <option value="barbados">Barbados</option>
    <option value="belarus">Belarus</option>
    <option value="belize">Belize</option>
    <option value="benin">Benin</option>
    <option value="bermuda">Bermuda</option>
    <option value="bhutan">Bhutan</option>
    <option value="bolivia">Bolivia</option>
    <option value="bosnia-and-herzegovina">Bosnia and Herzegovina</option>
    <option value="botswana">Botswana</option>
    <option value="brazil">Brazil</option>
    <option value="british-virgin-islands">British Virgin Islands</option>
    <option value="brunei">Brunei</option>
    <option value="burkina-faso">Burkina Faso</option>
    <option value="burundi">Burundi</option>
    <option value="cambodia">Cambodia</option>
    <option value="cameroon">Cameroon</option>
    <option value="canada">Canada</option>
    <option value="cape-verde">Cape Verde</option>
    <option value="cayman-islands">Cayman Islands</option>
    <option value="central-african-republic">Central African Republic</option>
    <option value="chad">Chad</option>
    <option value="chile">Chile</option>
    <option value="china">China</option>
    <option value="colombia">Colombia</option>
    <option value="comoros">Comoros</option>
    <option value="cook-islands">Cook Islands</option>
    <option value="costa-rica">Costa Rica</option>
    <option value="cote-divoire">Cote d'Ivoire</option>
    <option value="cuba">Cuba</option>
    <option value="democratic-republic-of-the-congo">Democratic Republic of the Congo</option>
    <option value="djibouti">Djibouti</option>
    <option value="dominica">Dominica</option>
    <option value="dominican-republic">Dominican Republic</option>
    <option value="ecuador">Ecuador</option>
    <option value="egypt">Egypt</option>
    <option value="el-salvador">El Salvador</option>
    <option value="equatorial-guinea">Equatorial Guinea</option>
    <option value="eritrea">Eritrea</option>
    <option value="eswatini">Eswatini</option>
    <option value="ethiopia">Ethiopia</option>
    <option value="falkland-islands">Falkland Islands</option>
    <option value="fiji">Fiji</option>
    <option value="gabon">Gabon</option>
    <option value="gambia">Gambia</option>
    <option value="georgia">Georgia</option>
    <option value="ghana">Ghana</option>
    <option value="greece">Greece</option>
    <option value="grenada">Grenada</option>
    <option value="guatemala">Guatemala</option>
    <option value="guinea">Guinea</option>
    <option value="guinea-bissau">Guinea Bissau</option>
    <option value="guyana">Guyana</option>
    <option value="haiti">Haiti</option>
    <option value="honduras">Honduras</option>
    <option value="hong-kong">Hong Kong</option>
    <option value="iceland">Iceland</option>
    <option value="india">India</option>
    <option value="indonesia">Indonesia</option>
    <option value="iran">Iran</option>
    <option value="iraq">Iraq</option>
    <option value="israel">Israel</option>
    <option value="jamaica">Jamaica</option>
    <option value="japan">Japan</option>
    <option value="jordan">Jordan</option>
    <option value="kazakhstan">Kazakhstan</option>
    <option value="kenya">Kenya</option>
    <option value="kiribati">Kiribati</option>
    <option value="kosovo">Kosovo</option>
    <option value="kyrgyzstan">Kyrgyzstan</option>
    <option value="laos">Laos</option>
    <option value="lebanon">Lebanon</option>
    <option value="lesotho">Lesotho</option>
    <option value="liberia">Liberia</option>
    <option value="libya">Libya</option>
    <option value="madagascar">Madagascar</option>
    <option value="malawi">Malawi</option>
    <option value="malaysia">Malaysia</option>
    <option value="maldives">Maldives</option>
    <option value="mali">Mali</option>
    <option value="marshall-islands">Marshall Islands</option>
    <option value="mauritania">Mauritania</option>
    <option value="mauritius">Mauritius</option>
    <option value="mexico">Mexico</option>
    <option value="micronesia">Micronesia</option>
    <option value="moldova">Moldova</option>
    <option value="mongolia">Mongolia</option>
    <option value="montenegro">Montenegro</option>
    <option value="montserrat">Montserrat</option>
    <option value="morocco">Morocco</option>
    <option value="mozambique">Mozambique</option>
    <option value="myanmar">Myanmar</option>
    <option value="namibia">Namibia</option>
    <option value="nauru">Nauru</option>
    <option value="nepal">Nepal</option>
    <option value="new-zealand">New Zealand</option>
    <option value="nicaragua">Nicaragua</option>
    <option value="niger">Niger</option>
    <option value="nigeria">Nigeria</option>
    <option value="north-macedonia">North Macedonia</option>
    <option value="occupied-palestinian-territories">Occupied Palestinian Territories</option>
    <option value="pakistan">Pakistan</option>
    <option value="palau">Palau</option>
    <option value="panama">Panama</option>
    <option value="papua-new-guinea">Papua New Guinea</option>
    <option value="paraguay">Paraguay</option>
    <option value="peru">Peru</option>
    <option value="philippines">Philippines</option>
    <option value="republic-of-congo">Republic of Congo</option>
    <option value="russia">Russia</option>
    <option value="rwanda">Rwanda</option>
    <option value="saint-helena-ascension-tristan-da-cunha">Saint Helena; Ascension; and Tristan da Cunha</option>
    <option value="saint-kitts-and-nevis">Saint Kitts and Nevis</option>
    <option value="saint-lucia">Saint Lucia</option>
    <option value="saint-vincent-and-the-grenadines">Saint Vincent and the Grenadines</option>
    <option value="samoa">Samoa</option>
    <option value="sao-tome-and-principe">Sao Tome and Principe</option>
    <option value="senegal">Senegal</option>
    <option value="serbia">Serbia</option>
    <option value="seychelles">Seychelles</option>
    <option value="sierra-leone">Sierra Leone</option>
    <option value="singapore">Singapore</option>
    <option value="solomon-islands">Solomon Islands</option>
    <option value="somalia">Somalia</option>
    <option value="somaliland">Somaliland</option>
    <option value="south-africa">South Africa</option>
    <option value="south-caucasus">South Caucasus</option>
    <option value="south-korea">South Korea</option>
    <option value="south-sudan">South Sudan</option>
    <option value="sri-lanka">Sri Lanka</option>
    <option value="sudan">Sudan</option>
    <option value="suriname">Suriname</option>
    <option value="syria">Syria</option>
    <option value="taiwan">Taiwan</option>
    <option value="tajikistan">Tajikistan</option>
    <option value="tanzania">Tanzania</option>
    <option value="thailand">Thailand</option>
    <option value="timor-leste">Timor-Leste</option>
    <option value="togo">Togo</option>
    <option value="tonga">Tonga</option>
    <option value="trinidad-and-tobago">Trinidad and Tobago</option>
    <option value="tunisia">Tunisia</option>
    <option value="turkey">Turkey</option>
    <option value="turkmenistan">Turkmenistan</option>
    <option value="turks-and-caicos-islands">Turks and Caicos Islands</option>
    <option value="tuvalu">Tuvalu</option>
    <option value="uganda">Uganda</option>
    <option value="ukraine">Ukraine</option>
    <option value="uruguay">Uruguay</option>
    <option value="uzbekistan">Uzbekistan</option>
    <option value="vanuatu">Vanuatu</option>
    <option value="venezuela">Venezuela</option>
    <option value="vietnam">Vietnam</option>
    <option value="yemen">Yemen</option>
    <option value="zambia">Zambia</option>
    <option value="zimbabwe">Zimbabwe</option>

</select>

Answer 1

You can use optgroup and data-attributes to group the countries and assign the point score.

document.querySelector('#select-country').addEventListener('change', e => {
  let opt = e.target.options[e.target.selectedIndex].closest('optgroup')
  let continent = opt.label
  let points = opt.dataset.points
  console.log(e.target.value, continent, points)
})

<select id="select-country" name="country">
  <option value="" selected="">Select country</option>
  <optgroup data-points='40' label="Africa">
    <option value="afghanistan">Afghanistan</option>
    <option value="albania">Albania</option>
    <option value="algeria">Algeria</option>
    <option value="angola">Angola</option>
  </optgroup>
  <optgroup data-points='50' label='Europe'>
    <option value="anguilla">Anguilla</option>
    <option value="antigua-and-barbuda">Antigua and Barbuda</option>
    <option value="argentina">Argentina</option>
    <option value="armenia">Armenia</option>
    <option value="australia">Australia</option>
    <option value="azerbaijan">Azerbaijan</option>
  </optgroup>

</select>