Question

我在注册工作，我有一个国家和州的下拉列表。我的问题是我不知道如何将默认国家设置为美国和美国的州。

我更改了element.length和element.option的值以及所选索引，但它不起作用。

样品

CODE

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);
        };
    }
}

Answer 1

http://jsfiddle.net/qw75h3vz/

检查一下：

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]);
         if(country_arr[i]=="USA") {
            countryElement.selectedIndex=countryElement.length-1;
            populateStates(countryElementId, stateElementId);
         }
    }

验证for循环中的if。

将国家和州的选定选项设置为美国

1 个答案: