在前端有些地方，例如表单里面，选择国家这一栏里面，往常实现这一功能，可能需要引入JS实现，但这样加载速度会变慢，所以需要我们不使用JS的情况下，实现这个功能。
下面是一个Demo:
<option value="Afghanistan (افغانستان)" data-countryname="Afghanistan (افغانستان)" data-countryiso="af">
Afghanistan (افغانستان)</option>
<option value="Åland Islands (Åland)" data-countryname="Åland Islands (Åland)" data-countryiso="ax">
Åland Islands (Åland)</option>
<option value="Albania (Shqipëri)" data-countryname="Albania (Shqipëri)" data-countryiso="al">
Albania (Shqipëri)</option>
<option value="Algeria (الجزائر)" data-countryname="Algeria (الجزائر)" data-countryiso="dz">
Algeria (الجزائر)</option>
<option value="American Samoa" data-countryname="American Samoa" data-countryiso="as">
American Samoa</option>
<option value="Andorra" data-countryname="Andorra" data-countryiso="ad">
Andorra</option>
<option value="Angola" data-countryname="Angola" data-countryiso="ao">
Angola</option>
<option value="Anguilla" data-countryname="Anguilla" data-countryiso="ai">
Anguilla</option>
<option value="Antigua and Barbuda" data-countryname="Antigua and Barbuda" data-countryiso="ag">
Antigua and Barbuda</option>
<option value="Argentina" data-countryname="Argentina" data-countryiso="ar">
Argentina</option>
<option value="Armenia (Հայաստան)" data-countryname="Armenia (Հայաստան)" data-countryiso="am">
Armenia (Հայաստան)</option>
<option value="Aruba" data-countryname="Aruba" data-countryiso="aw">
Aruba</option>
<option value="Australia" data-countryname="Australia" data-countryiso="au">
Australia</option>
<option value="Austria (Österreich)" data-countryname="Austria (Österreich)" data-countryiso="at">
Austria (Österreich)</option>
<option value="Azerbaijan (Azərbaycan)" data-countryname="Azerbaijan (Azərbaycan)" data-countryiso="az">
Azerbaijan (Azərbaycan)</option>
<option value="Bahamas" data-countryname="Bahamas" data-countryiso="bs">
Bahamas</option>
<option value="Bahrain (البحرين)" data-countryname="Bahrain (البحرين)" data-countryiso="bh">
Bahrain (البحرين)</option>
<option value="Bangladesh (বাংলাদেশ)" data-countryname="Bangladesh (বাংলাদেশ)" data-countryiso="bd">
Bangladesh (বাংলাদেশ)</option>
<option value="Barbados" data-countryname="Barbados" data-countryiso="bb">
Barbados</option>
<option value="Belarus (Беларусь)" data-countryname="Belarus (Беларусь)" data-countryiso="by">
Belarus (Беларусь)</option>
<option value="Belgium (België)" data-countryname="Belgium (België)" data-countryiso="be">
Belgium (België)</option>
<option value="Belize" data-countryname="Belize" data-countryiso="bz">
Belize</option>
<option value="Benin (Bénin)" data-countryname="Benin (Bénin)" data-countryiso="bj">
Benin (Bénin)</option>
<option value="Bermuda" data-countryname="Bermuda" data-countryiso="bm">
Bermuda</option>
<option value="Bhutan (འབྲུག)" data-countryname="Bhutan (འབྲུག)" data-countryiso="bt">
Bhutan (འབྲུག)</option>
<option value="Bolivia" data-countryname="Bolivia" data-countryiso="bo">
Bolivia</option>
<option value="Bosnia and Herzegovina (Босна и Херцеговина)" data-countryname="Bosnia and Herzegovina (Босна и Херцеговина)" data-countryiso="ba">
Bosnia and Herzegovina (Босна и Херцеговина)</option>
<option value="Botswana" data-countryname="Botswana" data-countryiso="bw">
Botswana</option>
<option value="Brazil (Brasil)" data-countryname="Brazil (Brasil)" data-countryiso="br">
Brazil (Brasil)</option>
<option value="British Indian Ocean Territory" data-countryname="British Indian Ocean Territory" data-countryiso="io">
British Indian Ocean Territory</option>
<option value="British Virgin Islands" data-countryname="British Virgin Islands" data-countryiso="vg">
British Virgin Islands</option>
<option value="Brunei" data-countryname="Brunei" data-countryiso="bn">
Brunei</option>
<option value="Bulgaria (България)" data-countryname="Bulgaria (България)" data-countryiso="bg">
Bulgaria (България)</option>
<option value="Burkina Faso" data-countryname="Burkina Faso" data-countryiso="bf">
Burkina Faso</option>
<option value="Burundi (Uburundi)" data-countryname="Burundi (Uburundi)" data-countryiso="bi">
Burundi (Uburundi)</option>
<option value="Cambodia (កម្ពុជា)" data-countryname="Cambodia (កម្ពុជា)" data-countryiso="kh">
Cambodia (កម្ពុជា)</option>
<option value="Cameroon (Cameroun)" data-countryname="Cameroon (Cameroun)" data-countryiso="cm">
Cameroon (Cameroun)</option>
<option value="Canada" data-countryname="Canada" data-countryiso="ca">
Canada</option>
<option value="Cape Verde (Kabu Verdi)" data-countryname="Cape Verde (Kabu Verdi)" data-countryiso="cv">
Cape Verde (Kabu Verdi)</option>
<option value="Caribbean Netherlands" data-countryname="Caribbean Netherlands" data-countryiso="bq">
Caribbean Netherlands</option>
<option value="Cayman Islands" data-countryname="Cayman Islands" data-countryiso="ky">
Cayman Islands</option>
<option value="Central African Republic (République Centrafricaine)" data-countryname="Central African Republic (République Centrafricaine)" data-countryiso="cf">
Central African Republic (République Centrafricaine)</option>
<option value="Chad (Tchad)" data-countryname="Chad (Tchad)" data-countryiso="td">
Chad (Tchad)</option>
<option value="Chile" data-countryname="Chile" data-countryiso="cl">
Chile</option>
<option value="China (中国)" data-countryname="China (中国)" data-countryiso="cn">
China (中国)</option>
<option value="Christmas Island" data-countryname="Christmas Island" data-countryiso="cx">
Christmas Island</option>
<option value="Cocos (Keeling) Islands (Kepulauan Cocos (Keeling))" data-countryname="Cocos (Keeling) Islands (Kepulauan Cocos (Keeling))" data-countryiso="cc">
Cocos (Keeling) Islands (Kepulauan Cocos (Keeling))</option>
<option value="Colombia" data-countryname="Colombia" data-countryiso="co">
Colombia</option>
<option value="Comoros (جزر القمر)" data-countryname="Comoros (جزر القمر)" data-countryiso="km">
Comoros (جزر القمر)</option>
<option value="Congo (DRC) (Jamhuri ya Kidemokrasia ya Kongo)" data-countryname="Congo (DRC) (Jamhuri ya Kidemokrasia ya Kongo)" data-countryiso="cd">
Congo (DRC) (Jamhuri ya Kidemokrasia ya Kongo)</option>
<option value="Congo (Republic) (Congo-Brazzaville)" data-countryname="Congo (Republic) (Congo-Brazzaville)" data-countryiso="cg">
Congo (Republic) (Congo-Brazzaville)</option>
<option value="Cook Islands" data-countryname="Cook Islands" data-countryiso="ck">
Cook Islands</option>
<option value="Costa Rica" data-countryname="Costa Rica" data-countryiso="cr">
Costa Rica</option>
<option value="Côte d’Ivoire" data-countryname="Côte d’Ivoire" data-countryiso="ci">
Côte d’Ivoire</option>
<option value="Croatia (Hrvatska)" data-countryname="Croatia (Hrvatska)" data-countryiso="hr">
Croatia (Hrvatska)</option>
<option value="Cuba" data-countryname="Cuba" data-countryiso="cu">
Cuba</option>
<option value="Curaçao" data-countryname="Curaçao" data-countryiso="cw">
Curaçao</option>
<option value="Cyprus (Κύπρος)" data-countryname="Cyprus (Κύπρος)" data-countryiso="cy">
Cyprus (Κύπρος)</option>
<option value="Czech Republic (Česká republika)" data-countryname="Czech Republic (Česká republika)" data-countryiso="cz">
Czech Republic (Česká republika)</option>
<option value="Denmark (Danmark)" data-countryname="Denmark (Danmark)" data-countryiso="dk">
Denmark (Danmark)</option>
<option value="Djibouti" data-countryname="Djibouti" data-countryiso="dj">
Djibouti</option>
<option value="Dominica" data-countryname="Dominica" data-countryiso="dm">
Dominica</option>
<option value="Dominican Republic (República Dominicana)" data-countryname="Dominican Republic (República Dominicana)" data-countryiso="do">
Dominican Republic (República Dominicana)</option>
<option value="Ecuador" data-countryname="Ecuador" data-countryiso="ec">
Ecuador</option>
<option value="Egypt (مصر)" data-countryname="Egypt (مصر)" data-countryiso="eg">
Egypt (مصر)</option>
<option value="El Salvador" data-countryname="El Salvador" data-countryiso="sv">
El Salvador</option>
<option value="Equatorial Guinea (Guinea Ecuatorial)" data-countryname="Equatorial Guinea (Guinea Ecuatorial)" data-countryiso="gq">
Equatorial Guinea (Guinea Ecuatorial)</option>
<option value="Eritrea" data-countryname="Eritrea" data-countryiso="er">
Eritrea</option>
<option value="Estonia (Eesti)" data-countryname="Estonia (Eesti)" data-countryiso="ee">
Estonia (Eesti)</option>
<option value="Ethiopia" data-countryname="Ethiopia" data-countryiso="et">
Ethiopia</option>
<option value="Falkland Islands (Islas Malvinas)" data-countryname="Falkland Islands (Islas Malvinas)" data-countryiso="fk">
Falkland Islands (Islas Malvinas)</option>
<option value="Faroe Islands (Føroyar)" data-countryname="Faroe Islands (Føroyar)" data-countryiso="fo">
Faroe Islands (Føroyar)</option>
<option value="Fiji" data-countryname="Fiji" data-countryiso="fj">
Fiji</option>
<option value="Finland (Suomi)" data-countryname="Finland (Suomi)" data-countryiso="fi">
Finland (Suomi)</option>
<option value="France" data-countryname="France" data-countryiso="fr">
France</option>
<option value="French Guiana (Guyane française)" data-countryname="French Guiana (Guyane française)" data-countryiso="gf">
French Guiana (Guyane française)</option>
<option value="French Polynesia (Polynésie française)" data-countryname="French Polynesia (Polynésie française)" data-countryiso="pf">
French Polynesia (Polynésie française)</option>
<option value="Gabon" data-countryname="Gabon" data-countryiso="ga">
Gabon</option>
<option value="Gambia" data-countryname="Gambia" data-countryiso="gm">
Gambia</option>
<option value="Georgia (საქართველო)" data-countryname="Georgia (საქართველო)" data-countryiso="ge">
Georgia (საქართველო)</option>
<option value="Germany (Deutschland)" data-countryname="Germany (Deutschland)" data-countryiso="de">
Germany (Deutschland)</option>
<option value="Ghana (Gaana)" data-countryname="Ghana (Gaana)" data-countryiso="gh">
Ghana (Gaana)</option>
<option value="Gibraltar" data-countryname="Gibraltar" data-countryiso="gi">
Gibraltar</option>
<option value="Greece (Ελλάδα)" data-countryname="Greece (Ελλάδα)" data-countryiso="gr">
Greece (Ελλάδα)</option>
<option value="Greenland (Kalaallit Nunaat)" data-countryname="Greenland (Kalaallit Nunaat)" data-countryiso="gl">
Greenland (Kalaallit Nunaat)</option>
<option value="Grenada" data-countryname="Grenada" data-countryiso="gd">
Grenada</option>
<option value="Guadeloupe" data-countryname="Guadeloupe" data-countryiso="gp">
Guadeloupe</option>
<option value="Guam" data-countryname="Guam" data-countryiso="gu">
Guam</option>
<option value="Guatemala" data-countryname="Guatemala" data-countryiso="gt">
Guatemala</option>
<option value="Guernsey" data-countryname="Guernsey" data-countryiso="gg">
Guernsey</option>
<option value="Guinea (Guinée)" data-countryname="Guinea (Guinée)" data-countryiso="gn">
Guinea (Guinée)</option>
<option value="Guinea-Bissau (Guiné Bissau)" data-countryname="Guinea-Bissau (Guiné Bissau)" data-countryiso="gw">
Guinea-Bissau (Guiné Bissau)</option>
<option value="Guyana" data-countryname="Guyana" data-countryiso="gy">
Guyana</option>
<option value="Haiti" data-countryname="Haiti" data-countryiso="ht">
Haiti</option>
<option value="Honduras" data-countryname="Honduras" data-countryiso="hn">
Honduras</option>
<option value="Hong Kong (香港)" data-countryname="Hong Kong (香港)" data-countryiso="hk">
Hong Kong (香港)</option>
<option value="Hungary (Magyarország)" data-countryname="Hungary (Magyarország)" data-countryiso="hu">
Hungary (Magyarország)</option>
<option value="Iceland (Ísland)" data-countryname="Iceland (Ísland)" data-countryiso="is">
Iceland (Ísland)</option>
<option value="India (भारत)" data-countryname="India (भारत)" data-countryiso="in">
India (भारत)</option>
<option value="Indonesia" data-countryname="Indonesia" data-countryiso="id">
Indonesia</option>
<option value="Iran (ایران)" data-countryname="Iran (ایران)" data-countryiso="ir">
Iran (ایران)</option>
<option value="Iraq (العراق)" data-countryname="Iraq (العراق)" data-countryiso="iq">
Iraq (العراق)</option>
<option value="Ireland" data-countryname="Ireland" data-countryiso="ie">
Ireland</option>
<option value="Isle of Man" data-countryname="Isle of Man" data-countryiso="im">
Isle of Man</option>
<option value="Israel (ישראל)" data-countryname="Israel (ישראל)" data-countryiso="il">
Israel (ישראל)</option>
<option value="Italy (Italia)" data-countryname="Italy (Italia)" data-countryiso="it">
Italy (Italia)</option>
<option value="Jamaica" data-countryname="Jamaica" data-countryiso="jm">
Jamaica</option>
<option value="Japan (日本)" data-countryname="Japan (日本)" data-countryiso="jp">
Japan (日本)</option>
<option value="Jersey" data-countryname="Jersey" data-countryiso="je">
Jersey</option>
<option value="Jordan (الأردن)" data-countryname="Jordan (الأردن)" data-countryiso="jo">
Jordan (الأردن)</option>
<option value="Kazakhstan (Казахстан)" data-countryname="Kazakhstan (Казахстан)" data-countryiso="kz">
Kazakhstan (Казахстан)</option>
<option value="Kenya" data-countryname="Kenya" data-countryiso="ke">
Kenya</option>
<option value="Kiribati" data-countryname="Kiribati" data-countryiso="ki">
Kiribati</option>
<option value="Kosovo (Kosovë)" data-countryname="Kosovo (Kosovë)" data-countryiso="xk">
Kosovo (Kosovë)</option>
<option value="Kuwait (الكويت)" data-countryname="Kuwait (الكويت)" data-countryiso="kw">
Kuwait (الكويت)</option>
<option value="Kyrgyzstan (Кыргызстан)" data-countryname="Kyrgyzstan (Кыргызстан)" data-countryiso="kg">
Kyrgyzstan (Кыргызстан)</option>
<option value="Laos (ລາວ)" data-countryname="Laos (ລາວ)" data-countryiso="la">
Laos (ລາວ)</option>
<option value="Latvia (Latvija)" data-countryname="Latvia (Latvija)" data-countryiso="lv">
Latvia (Latvija)</option>
<option value="Lebanon (لبنان)" data-countryname="Lebanon (لبنان)" data-countryiso="lb">
Lebanon (لبنان)</option>
<option value="Lesotho" data-countryname="Lesotho" data-countryiso="ls">
Lesotho</option>
<option value="Liberia" data-countryname="Liberia" data-countryiso="lr">
Liberia</option>
<option value="Libya (ليبيا)" data-countryname="Libya (ليبيا)" data-countryiso="ly">
Libya (ليبيا)</option>
<option value="Liechtenstein" data-countryname="Liechtenstein" data-countryiso="li">
Liechtenstein</option>
<option value="Lithuania (Lietuva)" data-countryname="Lithuania (Lietuva)" data-countryiso="lt">
Lithuania (Lietuva)</option>
<option value="Luxembourg" data-countryname="Luxembourg" data-countryiso="lu">
Luxembourg</option>
<option value="Macau (澳門)" data-countryname="Macau (澳門)" data-countryiso="mo">
Macau (澳門)</option>
<option value="Macedonia (FYROM) (Македонија)" data-countryname="Macedonia (FYROM) (Македонија)" data-countryiso="mk">
Macedonia (FYROM) (Македонија)</option>
<option value="Madagascar (Madagasikara)" data-countryname="Madagascar (Madagasikara)" data-countryiso="mg">
Madagascar (Madagasikara)</option>
<option value="Malawi" data-countryname="Malawi" data-countryiso="mw">
Malawi</option>
<option value="Malaysia" data-countryname="Malaysia" data-countryiso="my">
Malaysia</option>
<option value="Maldives" data-countryname="Maldives" data-countryiso="mv">
Maldives</option>
<option value="Mali" data-countryname="Mali" data-countryiso="ml">
Mali</option>
<option value="Malta" data-countryname="Malta" data-countryiso="mt">
Malta</option>
<option value="Marshall Islands" data-countryname="Marshall Islands" data-countryiso="mh">
Marshall Islands</option>
<option value="Martinique" data-countryname="Martinique" data-countryiso="mq">
Martinique</option>
<option value="Mauritania (موريتانيا)" data-countryname="Mauritania (موريتانيا)" data-countryiso="mr">
Mauritania (موريتانيا)</option>
<option value="Mauritius (Moris)" data-countryname="Mauritius (Moris)" data-countryiso="mu">
Mauritius (Moris)</option>
<option value="Mayotte" data-countryname="Mayotte" data-countryiso="yt">
Mayotte</option>
<option value="Mexico (México)" data-countryname="Mexico (México)" data-countryiso="mx">
Mexico (México)</option>
<option value="Micronesia" data-countryname="Micronesia" data-countryiso="fm">
Micronesia</option>
<option value="Moldova (Republica Moldova)" data-countryname="Moldova (Republica Moldova)" data-countryiso="md">
Moldova (Republica Moldova)</option>
<option value="Monaco" data-countryname="Monaco" data-countryiso="mc">
Monaco</option>
<option value="Mongolia (Монгол)" data-countryname="Mongolia (Монгол)" data-countryiso="mn">
Mongolia (Монгол)</option>
<option value="Montenegro (Crna Gora)" data-countryname="Montenegro (Crna Gora)" data-countryiso="me">
Montenegro (Crna Gora)</option>
<option value="Montserrat" data-countryname="Montserrat" data-countryiso="ms">
Montserrat</option>
<option value="Morocco (المغرب)" data-countryname="Morocco (المغرب)" data-countryiso="ma">
Morocco (المغرب)</option>
<option value="Mozambique (Moçambique)" data-countryname="Mozambique (Moçambique)" data-countryiso="mz">
Mozambique (Moçambique)</option>
<option value="Myanmar (Burma) (မြန်မာ)" data-countryname="Myanmar (Burma) (မြန်မာ)" data-countryiso="mm">
Myanmar (Burma) (မြန်မာ)</option>
<option value="Namibia (Namibië)" data-countryname="Namibia (Namibië)" data-countryiso="na">
Namibia (Namibië)</option>
<option value="Nauru" data-countryname="Nauru" data-countryiso="nr">
Nauru</option>
<option value="Nepal (नेपाल)" data-countryname="Nepal (नेपाल)" data-countryiso="np">
Nepal (नेपाल)</option>
<option value="Netherlands (Nederland)" data-countryname="Netherlands (Nederland)" data-countryiso="nl">
Netherlands (Nederland)</option>
<option value="New Caledonia (Nouvelle-Calédonie)" data-countryname="New Caledonia (Nouvelle-Calédonie)" data-countryiso="nc">
New Caledonia (Nouvelle-Calédonie)</option>
<option value="New Zealand" data-countryname="New Zealand" data-countryiso="nz">
New Zealand</option>
<option value="Nicaragua" data-countryname="Nicaragua" data-countryiso="ni">
Nicaragua</option>
<option value="Niger (Nijar)" data-countryname="Niger (Nijar)" data-countryiso="ne">
Niger (Nijar)</option>
<option value="Nigeria" data-countryname="Nigeria" data-countryiso="ng">
Nigeria</option>
<option value="Niue" data-countryname="Niue" data-countryiso="nu">
Niue</option>
<option value="Norfolk Island" data-countryname="Norfolk Island" data-countryiso="nf">
Norfolk Island</option>
<option value="North Korea (조선 민주주의 인민 공화국)" data-countryname="North Korea (조선 민주주의 인민 공화국)" data-countryiso="kp">
North Korea (조선 민주주의 인민 공화국)</option>
<option value="Northern Mariana Islands" data-countryname="Northern Mariana Islands" data-countryiso="mp">
Northern Mariana Islands</option>
<option value="Norway (Norge)" data-countryname="Norway (Norge)" data-countryiso="no">
Norway (Norge)</option>
<option value="Oman (عُمان)" data-countryname="Oman (عُمان)" data-countryiso="om">
Oman (عُمان)</option>
<option value="Pakistan (پاکستان)" data-countryname="Pakistan (پاکستان)" data-countryiso="pk">
Pakistan (پاکستان)</option>
<option value="Palau" data-countryname="Palau" data-countryiso="pw">
Palau</option>
<option value="Palestine (فلسطين)" data-countryname="Palestine (فلسطين)" data-countryiso="ps">
Palestine (فلسطين)</option>
<option value="Panama (Panamá)" data-countryname="Panama (Panamá)" data-countryiso="pa">
Panama (Panamá)</option>
<option value="Papua New Guinea" data-countryname="Papua New Guinea" data-countryiso="pg">
Papua New Guinea</option>
<option value="Paraguay" data-countryname="Paraguay" data-countryiso="py">
Paraguay</option>
<option value="Peru (Perú)" data-countryname="Peru (Perú)" data-countryiso="pe">
Peru (Perú)</option>
<option value="Philippines" data-countryname="Philippines" data-countryiso="ph">
Philippines</option>
<option value="Pitcairn Islands" data-countryname="Pitcairn Islands" data-countryiso="pn">
Pitcairn Islands</option>
<option value="Poland (Polska)" data-countryname="Poland (Polska)" data-countryiso="pl">
Poland (Polska)</option>
<option value="Portugal" data-countryname="Portugal" data-countryiso="pt">
Portugal</option>
<option value="Puerto Rico" data-countryname="Puerto Rico" data-countryiso="pr">
Puerto Rico</option>
<option value="Qatar (قطر)" data-countryname="Qatar (قطر)" data-countryiso="qa">
Qatar (قطر)</option>
<option value="Réunion (La Réunion)" data-countryname="Réunion (La Réunion)" data-countryiso="re">
Réunion (La Réunion)</option>
<option value="Romania (România)" data-countryname="Romania (România)" data-countryiso="ro">
Romania (România)</option>
<option value="Russia (Россия)" data-countryname="Russia (Россия)" data-countryiso="ru">
Russia (Россия)</option>
<option value="Rwanda" data-countryname="Rwanda" data-countryiso="rw">
Rwanda</option>
<option value="Saint Barthélemy (Saint-Barthélemy)" data-countryname="Saint Barthélemy (Saint-Barthélemy)" data-countryiso="bl">
Saint Barthélemy (Saint-Barthélemy)</option>
<option value="Saint Helena" data-countryname="Saint Helena" data-countryiso="sh">
Saint Helena</option>
<option value="Saint Kitts and Nevis" data-countryname="Saint Kitts and Nevis" data-countryiso="kn">
Saint Kitts and Nevis</option>
<option value="Saint Lucia" data-countryname="Saint Lucia" data-countryiso="lc">
Saint Lucia</option>
<option value="Saint Martin (Saint-Martin (partie française))" data-countryname="Saint Martin (Saint-Martin (partie française))" data-countryiso="mf">
Saint Martin (Saint-Martin (partie française))</option>
<option value="Saint Pierre and Miquelon (Saint-Pierre-et-Miquelon)" data-countryname="Saint Pierre and Miquelon (Saint-Pierre-et-Miquelon)" data-countryiso="pm">
Saint Pierre and Miquelon (Saint-Pierre-et-Miquelon)</option>
<option value="Saint Vincent and the Grenadines" data-countryname="Saint Vincent and the Grenadines" data-countryiso="vc">
Saint Vincent and the Grenadines</option>
<option value="Samoa" data-countryname="Samoa" data-countryiso="ws">
Samoa</option>
<option value="San Marino" data-countryname="San Marino" data-countryiso="sm">
San Marino</option>
<option value="São Tomé and Príncipe (São Tomé e Príncipe)" data-countryname="São Tomé and Príncipe (São Tomé e Príncipe)" data-countryiso="st">
São Tomé and Príncipe (São Tomé e Príncipe)</option>
<option value="Saudi Arabia (المملكة العربية السعودية)" data-countryname="Saudi Arabia (المملكة العربية السعودية)" data-countryiso="sa">
Saudi Arabia (المملكة العربية السعودية)</option>
<option value="Senegal (Sénégal)" data-countryname="Senegal (Sénégal)" data-countryiso="sn">
Senegal (Sénégal)</option>
<option value="Serbia (Србија)" data-countryname="Serbia (Србија)" data-countryiso="rs">
Serbia (Србија)</option>
<option value="Seychelles" data-countryname="Seychelles" data-countryiso="sc">
Seychelles</option>
<option value="Sierra Leone" data-countryname="Sierra Leone" data-countryiso="sl">
Sierra Leone</option>
<option value="Singapore" data-countryname="Singapore" data-countryiso="sg">
Singapore</option>
<option value="Sint Maarten" data-countryname="Sint Maarten" data-countryiso="sx">
Sint Maarten</option>
<option value="Slovakia (Slovensko)" data-countryname="Slovakia (Slovensko)" data-countryiso="sk">
Slovakia (Slovensko)</option>
<option value="Slovenia (Slovenija)" data-countryname="Slovenia (Slovenija)" data-countryiso="si">
Slovenia (Slovenija)</option>
<option value="Solomon Islands" data-countryname="Solomon Islands" data-countryiso="sb">
Solomon Islands</option>
<option value="Somalia (Soomaaliya)" data-countryname="Somalia (Soomaaliya)" data-countryiso="so">
Somalia (Soomaaliya)</option>
<option value="South Africa" data-countryname="South Africa" data-countryiso="za">
South Africa</option>
<option value="South Georgia & South Sandwich Islands" data-countryname="South Georgia & South Sandwich Islands" data-countryiso="gs">
South Georgia & South Sandwich Islands</option>
<option value="South Korea (대한민국)" data-countryname="South Korea (대한민국)" data-countryiso="kr">
South Korea (대한민국)</option>
<option value="South Sudan (جنوب السودان)" data-countryname="South Sudan (جنوب السودان)" data-countryiso="ss">
South Sudan (جنوب السودان)</option>
<option value="Spain (España)" data-countryname="Spain (España)" data-countryiso="es">
Spain (España)</option>
<option value="Sri Lanka (ශ්රී ලංකාව)" data-countryname="Sri Lanka (ශ්රී ලංකාව)" data-countryiso="lk">
Sri Lanka (ශ්රී ලංකාව)</option>
<option value="Sudan (السودان)" data-countryname="Sudan (السودان)" data-countryiso="sd">
Sudan (السودان)</option>
<option value="Suriname" data-countryname="Suriname" data-countryiso="sr">
Suriname</option>
<option value="Svalbard and Jan Mayen (Svalbard og Jan Mayen)" data-countryname="Svalbard and Jan Mayen (Svalbard og Jan Mayen)" data-countryiso="sj">
Svalbard and Jan Mayen (Svalbard og Jan Mayen)</option>
<option value="Swaziland (Kingdom of eSwatini)" data-countryname="Swaziland (Kingdom of eSwatini)" data-countryiso="sz">
Swaziland (Kingdom of eSwatini)</option>
<option value="Sweden (Sverige)" data-countryname="Sweden (Sverige)" data-countryiso="se">
Sweden (Sverige)</option>
<option value="Switzerland (Schweiz/Suisse/Svizzera)" data-countryname="Switzerland (Schweiz/Suisse/Svizzera)" data-countryiso="ch">
Switzerland (Schweiz/Suisse/Svizzera)</option>
<option value="Syria (سوريا)" data-countryname="Syria (سوريا)" data-countryiso="sy">
Syria (سوريا)</option>
<option value="Taiwan (台灣)" data-countryname="Taiwan (台灣)" data-countryiso="tw">
Taiwan (台灣)</option>
<option value="Tajikistan" data-countryname="Tajikistan" data-countryiso="tj">
Tajikistan</option>
<option value="Tanzania" data-countryname="Tanzania" data-countryiso="tz">
Tanzania</option>
<option value="Thailand (ไทย)" data-countryname="Thailand (ไทย)" data-countryiso="th">
Thailand (ไทย)</option>
<option value="Timor-Leste" data-countryname="Timor-Leste" data-countryiso="tl">
Timor-Leste</option>
<option value="Togo" data-countryname="Togo" data-countryiso="tg">
Togo</option>
<option value="Tokelau" data-countryname="Tokelau" data-countryiso="tk">
Tokelau</option>
<option value="Tonga" data-countryname="Tonga" data-countryiso="to">
Tonga</option>
<option value="Trinidad and Tobago" data-countryname="Trinidad and Tobago" data-countryiso="tt">
Trinidad and Tobago</option>
<option value="Tunisia (تونس)" data-countryname="Tunisia (تونس)" data-countryiso="tn">
Tunisia (تونس)</option>
<option value="Turkey (Türkiye)" data-countryname="Turkey (Türkiye)" data-countryiso="tr">
Turkey (Türkiye)</option>
<option value="Turkmenistan" data-countryname="Turkmenistan" data-countryiso="tm">
Turkmenistan</option>
<option value="Turks and Caicos Islands" data-countryname="Turks and Caicos Islands" data-countryiso="tc">
Turks and Caicos Islands</option>
<option value="Tuvalu" data-countryname="Tuvalu" data-countryiso="tv">
Tuvalu</option>
<option value="Uganda" data-countryname="Uganda" data-countryiso="ug">
Uganda</option>
<option value="Ukraine (Україна)" data-countryname="Ukraine (Україна)" data-countryiso="ua">
Ukraine (Україна)</option>
<option value="United Arab Emirates (الإمارات العربية المتحدة)" data-countryname="United Arab Emirates (الإمارات العربية المتحدة)" data-countryiso="ae">
United Arab Emirates (الإمارات العربية المتحدة)</option>
<option value="United Kingdom" data-countryname="United Kingdom" data-countryiso="gb">
United Kingdom</option>
<option value="United States" data-countryname="United States" data-countryiso="us">
United States</option>
<option value="U.S. Minor Outlying Islands" data-countryname="U.S. Minor Outlying Islands" data-countryiso="um">
U.S. Minor Outlying Islands</option>
<option value="U.S. Virgin Islands" data-countryname="U.S. Virgin Islands" data-countryiso="vi">
U.S. Virgin Islands</option>
<option value="Uruguay" data-countryname="Uruguay" data-countryiso="uy">
Uruguay</option>
<option value="Uzbekistan (Oʻzbekiston)" data-countryname="Uzbekistan (Oʻzbekiston)" data-countryiso="uz">
Uzbekistan (Oʻzbekiston)</option>
<option value="Vanuatu" data-countryname="Vanuatu" data-countryiso="vu">
Vanuatu</option>
<option value="Vatican City (Città del Vaticano)" data-countryname="Vatican City (Città del Vaticano)" data-countryiso="va">
Vatican City (Città del Vaticano)</option>
<option value="Venezuela" data-countryname="Venezuela" data-countryiso="ve">
Venezuela</option>
<option value="Vietnam (Việt Nam)" data-countryname="Vietnam (Việt Nam)" data-countryiso="vn">
Vietnam (Việt Nam)</option>
<option value="Wallis and Futuna" data-countryname="Wallis and Futuna" data-countryiso="wf">
Wallis and Futuna</option>
<option value="Western Sahara (الصحراء الغربية)" data-countryname="Western Sahara (الصحراء الغربية)" data-countryiso="eh">
Western Sahara (الصحراء الغربية)</option>
<option value="Yemen (اليمن)" data-countryname="Yemen (اليمن)" data-countryiso="ye">
Yemen (اليمن)</option>
<option value="Zambia" data-countryname="Zambia" data-countryiso="zm">
Zambia</option>
<option value="Zimbabwe" data-countryname="Zimbabwe" data-countryiso="zw">
Zimbabwe</option>
以上是实现Select选项一种方法，我这里提供一个国家缩写 : 国家名称组合
AA : America
AD : Andorra
AE : United Arab Emirates
AF : Afghanistan
AG : Antigua and Barbuda
AL : Albania
AM : Armenia
AO : Angola
AR : Argentina
AT : Austria
AU : Australia
AW : Aruba
AZ : Azerbaijan
BA : Bosnia and Herzegovina
BB : Barbados
BD : Bangladesh
BE : Belgium
BF : Burkina Faso
BG : Bulgaria
BH : Bahrain
BI : Burundi
BJ : Benin
BM : Bermuda
BN : Brunei
BO : Bolivia
BR : Brazil
BS : Bahamas
BT : Bhutan
BW : Botswana
BY : Belarus
BZ : Belize
CA : Canada
CD : Democratic Republic of the Congo
CF : Central African Republic
CG : Democratic Republic of the Congo
CH : Switzerland
CL : Chile
CM : Cameroon
CN : China
CO : Colombia
CR : Costa Rica
CU : Cuba
CV : Cape Verde
CY : Cyprus
CZ : Czech Republic
DE : Germany
DJ : Djibouti
DK : Denmark
DM : Dominica
DO : Dominican Republic
DZ : Algeria
EC : Ecuador
EE : Estonia
EG : Egypt
ER : Eritrea
ES : Spain
ET : Ethiopia
FI : Finland
FJ : Fiji
FK : Falkland Islands
FM : Micronesia
FO : Faroe Islands
FR : France
GA : Gabon
GB : United Kingdom
GD : Grenada
GE : Georgia
GH : Ghana
GI : Gibraltar
GM : Gambia
GN : Guinea
GQ : Equatorial Guinea
GR : Greece
GT : Guatemala
GW : Guinea-Bissau
GY : Guyana
HK : Hong Kong
HN : Honduras
HR : Croatia
HT : Haiti
HU : Hungary
ID : Indonesia
IE : Ireland
IL : Israel
IN : India
IQ : Iraq
IR : Iran
IS : Iceland
IT : Italy
JM : Jamaica
JO : Jordan
JP : Japan
KE : Kenya
KG : Kyrgyzstan
KH : Cambodia
KI : Kiribati
KM : Comoros
KN : Saint Kitts and Nevis
KP : North Korea
KR : South Korea
KW : Kuwait
KY : Cayman Islands
KZ : Kazakhstan
LA : Laos
LB : Lebanon
LC : Saint Lucia
LI : Liechtenstein
LK : Sri Lanka
LR : Liberia
LS : Lesotho
LT : Lithuania
LU : Luxembourg
LV : Latvia
LY : Libya
MA : Morocco
MC : Monaco
MD : Moldova
ME : Montenegro
MG : Madagascar
MK : Macedonia
ML : Mali
MM : Myanmar
MN : Mongolia
MO : Macao
MR : Mauritania
MT : Malta
MU : Mauritius
MV : Maldives
MW : Malawi
MX : Mexico
MY : Malaysia
MZ : Mozambique
NA : Namibia
NE : Niger
NG : Nigeria
NI : Nicaragua
NL : Netherlands
NO : Norway
NP : Nepal
NR : Nauru
NZ : New Zealand
OM : Oman
PA : Panama
PE : Peru
PG : Papua New Guinea
PH : Philippines
PK : Pakistan
PL : Poland
PR : Puerto Rico
PS : Palestine
PT : Portugal
PW : Palau
PY : Paraguay
QA : Qatar
RO : Romania
RS : Serbia
RU : Russia
RW : Rwanda
SA : Saudi Arabia
SB : Solomon Islands
SC : Seychelles
SD : Sudan
SE : Sweden
SG : Singapore
SI : Slovenia
SK : Slovak Republic
SL : Sierra Leone
SM : San Marino
SN : Senegal
SO : Somalia
SR : Suriname
ST : Sao Tome and Principe
SV : El Salvador
SY : Syria
SZ : Swaziland
TD : Chad
TG : Togo
TH : Thailand
TJ : Tajikistan
TM : Turkmenistan
TN : Tunisia
TO : Tonga
TR : Turkey
TT : Trinidad and Tobago
TV : Tuvalu
TW : Taiwan
TZ : Tanzania
UA : Ukraine
UG : Uganda
UY : Uruguay
UZ : Uzbekistan
VC : Saint Vincent And The Grenadine
VE : Venezuela
VG : British Virgin Islands
VN : Vietnam
VU : Vanuatu
WF : Wallis and Futuna
WS : Western Samoa
YE : Yemen
ZA : South Africa
ZM : Zambia
ZW : Zimbabwe