javascript - javascript 中无法出现下拉菜单？

Question

我想实现国家和州下拉菜单。在我的脚本中，我还包含了 javascript 代码和 html 表单。此代码取自JSfiddle

在这个jsfiddle中，一切都很好。但我的脚本无法正常工作。它不会动态显示国家/地区和州。

    
// Countries
var country_arr = new Array("Afghanistan", "Albania", "Algeria", "American Samoa", "Angola", "Anguilla", "Antartica", "Antigua and Barbuda", "Argentina", "Armenia", "Aruba", "Ashmore and Cartier Island", "Australia", "Austria", "Azerbaijan", "Bahamas", "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia", "Bosnia and Herzegovina", "Botswana", "Brazil", "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burma", "Burundi", "Cambodia", "Cameroon", "Canada", "Cape Verde", "Cayman Islands", "Central African Republic", "Chad", "Chile", "China", "Christmas Island", "Clipperton Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo, Democratic Republic of the", "Congo, Republic of the", "Cook Islands", "Costa Rica", "Cote d'Ivoire", "Croatia", "Cuba", "Cyprus", "Czeck Republic", "Denmark", "Djibouti", "Dominica", "Dominican Republic", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia", "Europa Island", "Falkland Islands (Islas Malvinas)", "Faroe Islands", "Fiji", "Finland", "France", "French Guiana", "French Polynesia", "French Southern and Antarctic Lands", "Gabon", "Gambia, The", "Gaza Strip", "Georgia", "Germany", "Ghana", "Gibraltar", "Glorioso Islands", "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guernsey", "Guinea", "Guinea-Bissau", "Guyana", "Haiti", "Heard Island and McDonald Islands", "Holy See (Vatican City)", "Honduras", "Hong Kong", "Howland Island", "Hungary", "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Ireland, Northern", "Israel", "Italy", "Jamaica", "Jan Mayen", "Japan", "Jarvis Island", "Jersey", "Johnston Atoll", "Jordan", "Juan de Nova Island", "Kazakhstan", "Kenya", "Kiribati", "Korea, North", "Korea, South", "Kuwait", "Kyrgyzstan", "Laos", "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg", "Macau", "Macedonia, Former Yugoslav Republic of", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Man, Isle of", "Marshall Islands", "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia, Federated States of", "Midway Islands", "Moldova", "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Namibia", "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand", "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "Northern Mariana Islands", "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Pitcaim Islands", "Poland", "Portugal", "Puerto Rico", "Qatar", "Reunion", "Romainia", "Russia", "Rwanda", "Saint Helena", "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon", "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Sao Tome and Principe", "Saudi Arabia", "Scotland", "Senegal", "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands", "Somalia", "South Africa", "South Georgia and South Sandwich Islands", "Spain", "Spratly Islands", "Sri Lanka", "Sudan", "Suriname", "Svalbard", "Swaziland", "Sweden", "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "Tobago", "Toga", "Tokelau", "Tonga", "Trinidad", "Tunisia", "Turkey", "Turkmenistan", "Tuvalu", "Uganda", "Ukraine", "United Arab Emirates", "United Kingdom", "Uruguay", "USA", "Uzbekistan", "Vanuatu", "Venezuela", "Vietnam", "Virgin Islands", "Wales", "Wallis and Futuna", "West Bank", "Western Sahara", "Yemen", "Yugoslavia", "Zambia", "Zimbabwe");

// States
var s_a = new Array();
s_a[0] = "";
s_a[1] = "Badakhshan|Badghis|Baghlan|Balkh|Bamian|Farah|Faryab|Ghazni|Ghowr|Helmand|Herat|Jowzjan|Kabol|Kandahar|Kapisa|Konar|Kondoz|Laghman|Lowgar|Nangarhar|Nimruz|Oruzgan|Paktia|Paktika|Parvan|Samangan|Sar-e Pol|Takhar|Vardak|Zabol";
s_a[2] = "Berat|Bulqize|Delvine|Devoll (Bilisht)|Diber (Peshkopi)|Durres|Elbasan|Fier|Gjirokaster|Gramsh|Has (Krume)|Kavaje|Kolonje (Erseke)|Korce|Kruje|Kucove|Kukes|Kurbin|Lezhe|Librazhd|Lushnje|Malesi e Madhe (Koplik)|Mallakaster (Ballsh)|Mat (Burrel)|Mirdite (Rreshen)|Peqin|Permet|Pogradec|Puke|Sarande|Shkoder|Skrapar (Corovode)|Tepelene|Tirane (Tirana)|Tirane (Tirana)|Tropoje (Bajram Curri)|Vlore";
s_a[3] = "Adrar|Ain Defla|Ain Temouchent|Alger|Annaba|Batna|Bechar|Bejaia|Biskra|Blida|Bordj Bou Arreridj|Bouira|Boumerdes|Chlef|Constantine|Djelfa|El Bayadh|El Oued|El Tarf|Ghardaia|Guelma|Illizi|Jijel|Khenchela|Laghouat|M'Sila|Mascara|Medea|Mila|Mostaganem|Naama|Oran|Ouargla|Oum el Bouaghi|Relizane|Saida|Setif|Sidi Bel Abbes|Skikda|Souk Ahras|Tamanghasset|Tebessa|Tiaret|Tindouf|Tipaza|Tissemsilt|Tizi Ouzou|Tlemcen";
/**s_a[4] ....
....
....
....**/
s_a[252] = "Bulawayo|Harare|ManicalandMashonaland Central|Mashonaland East|Mashonaland West|Masvingo|Matabeleland North|Matabeleland South|Midlands";


function populateStates(countryElementId, stateElementId) {

    var selectedCountryIndex = document.getElementById(countryElementId).selectedIndex;

    var stateElement = document.getElementById(stateElementId);

    stateElement.length = 0; // Fixed by Julian Woods
    stateElement.options[0] = new Option('Select State', '');
    stateElement.selectedIndex = 0;

    var state_arr = s_a[selectedCountryIndex].split("|");

    for (var i = 0; i < state_arr.length; i++) {
        stateElement.options[stateElement.length] = new Option(state_arr[i], state_arr[i]);
    }
}

function populateCountries(countryElementId, stateElementId) {
    // given the id of the <select> tag as function argument, it inserts <option> tags
    var countryElement = document.getElementById(countryElementId);
    countryElement.length = 0;
    countryElement.options[0] = new Option('Select Country', '-1');
    countryElement.selectedIndex = 0;
    for (var i = 0; i < country_arr.length; i++) {
        countryElement.options[countryElement.length] = new Option(country_arr[i], country_arr[i]);
    }

    // Assigned all countries. Now assign event listener for the states.

    if (stateElementId) {
        countryElement.onchange = function () {
            populateStates(countryElementId, stateElementId);
        };
    }
}


populateCountries("country", "state");
populateCountries("country2");

<div>
    Country: <select id="country" name="country"></select>
    State: <select name="state" id="state"></select>  
 </div>

输出:

Answer 1

它将通过调用页面底部的函数来工作，检查这个

注意:它仅适用于前 4 个国家/地区(因为在此示例中仅初始化了前 4 个国家/地区的州)

    // Countries
var country_arr = new Array("Afghanistan", "Albania", "Algeria", "American Samoa", "Angola", "Anguilla", "Antartica", "Antigua and Barbuda", "Argentina", "Armenia", "Aruba", "Ashmore and Cartier Island", "Australia", "Austria", "Azerbaijan", "Bahamas", "Bahrain", "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin", "Bermuda", "Bhutan", "Bolivia", "Bosnia and Herzegovina", "Botswana", "Brazil", "British Virgin Islands", "Brunei", "Bulgaria", "Burkina Faso", "Burma", "Burundi", "Cambodia", "Cameroon", "Canada", "Cape Verde", "Cayman Islands", "Central African Republic", "Chad", "Chile", "China", "Christmas Island", "Clipperton Island", "Cocos (Keeling) Islands", "Colombia", "Comoros", "Congo, Democratic Republic of the", "Congo, Republic of the", "Cook Islands", "Costa Rica", "Cote d'Ivoire", "Croatia", "Cuba", "Cyprus", "Czeck Republic", "Denmark", "Djibouti", "Dominica", "Dominican Republic", "Ecuador", "Egypt", "El Salvador", "Equatorial Guinea", "Eritrea", "Estonia", "Ethiopia", "Europa Island", "Falkland Islands (Islas Malvinas)", "Faroe Islands", "Fiji", "Finland", "France", "French Guiana", "French Polynesia", "French Southern and Antarctic Lands", "Gabon", "Gambia, The", "Gaza Strip", "Georgia", "Germany", "Ghana", "Gibraltar", "Glorioso Islands", "Greece", "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala", "Guernsey", "Guinea", "Guinea-Bissau", "Guyana", "Haiti", "Heard Island and McDonald Islands", "Holy See (Vatican City)", "Honduras", "Hong Kong", "Howland Island", "Hungary", "Iceland", "India", "Indonesia", "Iran", "Iraq", "Ireland", "Ireland, Northern", "Israel", "Italy", "Jamaica", "Jan Mayen", "Japan", "Jarvis Island", "Jersey", "Johnston Atoll", "Jordan", "Juan de Nova Island", "Kazakhstan", "Kenya", "Kiribati", "Korea, North", "Korea, South", "Kuwait", "Kyrgyzstan", "Laos", "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya", "Liechtenstein", "Lithuania", "Luxembourg", "Macau", "Macedonia, Former Yugoslav Republic of", "Madagascar", "Malawi", "Malaysia", "Maldives", "Mali", "Malta", "Man, Isle of", "Marshall Islands", "Martinique", "Mauritania", "Mauritius", "Mayotte", "Mexico", "Micronesia, Federated States of", "Midway Islands", "Moldova", "Monaco", "Mongolia", "Montserrat", "Morocco", "Mozambique", "Namibia", "Nauru", "Nepal", "Netherlands", "Netherlands Antilles", "New Caledonia", "New Zealand", "Nicaragua", "Niger", "Nigeria", "Niue", "Norfolk Island", "Northern Mariana Islands", "Norway", "Oman", "Pakistan", "Palau", "Panama", "Papua New Guinea", "Paraguay", "Peru", "Philippines", "Pitcaim Islands", "Poland", "Portugal", "Puerto Rico", "Qatar", "Reunion", "Romainia", "Russia", "Rwanda", "Saint Helena", "Saint Kitts and Nevis", "Saint Lucia", "Saint Pierre and Miquelon", "Saint Vincent and the Grenadines", "Samoa", "San Marino", "Sao Tome and Principe", "Saudi Arabia", "Scotland", "Senegal", "Seychelles", "Sierra Leone", "Singapore", "Slovakia", "Slovenia", "Solomon Islands", "Somalia", "South Africa", "South Georgia and South Sandwich Islands", "Spain", "Spratly Islands", "Sri Lanka", "Sudan", "Suriname", "Svalbard", "Swaziland", "Sweden", "Switzerland", "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand", "Tobago", "Toga", "Tokelau", "Tonga", "Trinidad", "Tunisia", "Turkey", "Turkmenistan", "Tuvalu", "Uganda", "Ukraine", "United Arab Emirates", "United Kingdom", "Uruguay", "USA", "Uzbekistan", "Vanuatu", "Venezuela", "Vietnam", "Virgin Islands", "Wales", "Wallis and Futuna", "West Bank", "Western Sahara", "Yemen", "Yugoslavia", "Zambia", "Zimbabwe");

// States
var s_a = new Array();
s_a[0] = "";
s_a[1] = "Badakhshan|Badghis|Baghlan|Balkh|Bamian|Farah|Faryab|Ghazni|Ghowr|Helmand|Herat|Jowzjan|Kabol|Kandahar|Kapisa|Konar|Kondoz|Laghman|Lowgar|Nangarhar|Nimruz|Oruzgan|Paktia|Paktika|Parvan|Samangan|Sar-e Pol|Takhar|Vardak|Zabol";
s_a[2] = "Berat|Bulqize|Delvine|Devoll (Bilisht)|Diber (Peshkopi)|Durres|Elbasan|Fier|Gjirokaster|Gramsh|Has (Krume)|Kavaje|Kolonje (Erseke)|Korce|Kruje|Kucove|Kukes|Kurbin|Lezhe|Librazhd|Lushnje|Malesi e Madhe (Koplik)|Mallakaster (Ballsh)|Mat (Burrel)|Mirdite (Rreshen)|Peqin|Permet|Pogradec|Puke|Sarande|Shkoder|Skrapar (Corovode)|Tepelene|Tirane (Tirana)|Tirane (Tirana)|Tropoje (Bajram Curri)|Vlore";
s_a[3] = "Adrar|Ain Defla|Ain Temouchent|Alger|Annaba|Batna|Bechar|Bejaia|Biskra|Blida|Bordj Bou Arreridj|Bouira|Boumerdes|Chlef|Constantine|Djelfa|El Bayadh|El Oued|El Tarf|Ghardaia|Guelma|Illizi|Jijel|Khenchela|Laghouat|M'Sila|Mascara|Medea|Mila|Mostaganem|Naama|Oran|Ouargla|Oum el Bouaghi|Relizane|Saida|Setif|Sidi Bel Abbes|Skikda|Souk Ahras|Tamanghasset|Tebessa|Tiaret|Tindouf|Tipaza|Tissemsilt|Tizi Ouzou|Tlemcen";

s_a[252] = "Bulawayo|Harare|ManicalandMashonaland Central|Mashonaland East|Mashonaland West|Masvingo|Matabeleland North|Matabeleland South|Midlands";


function populateStates(countryElementId, stateElementId) {

    var selectedCountryIndex = document.getElementById(countryElementId).selectedIndex;

    var stateElement = document.getElementById(stateElementId);

    stateElement.length = 0; // Fixed by Julian Woods
    stateElement.options[0] = new Option('Select State', '');
    stateElement.selectedIndex = 0;

    var state_arr = s_a[selectedCountryIndex].split("|");

    for (var i = 0; i < state_arr.length; i++) {
        stateElement.options[stateElement.length] = new Option(state_arr[i], state_arr[i]);
    }
}

function populateCountries(countryElementId, stateElementId) {
    // given the id of the <select> tag as function argument, it inserts <option> tags
    var countryElement = document.getElementById(countryElementId);
    countryElement.length = 0;
    countryElement.options[0] = new Option('Select Country', '-1');
    countryElement.selectedIndex = 0;
    for (var i = 0; i < country_arr.length; i++) {
        countryElement.options[countryElement.length] = new Option(country_arr[i], country_arr[i]);
    }

    // Assigned all countries. Now assign event listener for the states.

    if (stateElementId) {
        countryElement.onchange = function () {
            populateStates(countryElementId, stateElementId);
        };
    }
}


    populateCountries("country", "state");
    //populateCountries("country2");

<div>
    Country:
    <select id="country" name="country"></select>
    State:
    <select name="state" id="state"></select>          
 </div>