var regionOption = document.querySelector("#municipality");
var districtOption = document.querySelector("#districtName");
var provOption = document.querySelector("#region");

createOption(provOption, Object.keys(regions));

provOption.addEventListener('change', function() {
    createOption(regionOption, regions[provOption.value]);
});
regionOption.addEventListener('change', function() {
      createOption(districtOption, districts[regionOption.value]);
});
function createOption(dropDown, options) {
    dropDown.innerHTML = '';
        options.forEach(function(value) {
            dropDown.innerHTML += '<option name="' + value + '">' + value + '</option>';
        });
};

CSS：

<select id="region" style="width: 125px;"></select>
<select id="municipality" style="width: 125px;"></select>
<select id="districtName" style="width: 125px;"></select>

因此，我正在为空选择填充选项，我想知道如何获得所选选项的值。我基本上想检查是否（select value = 'A' && another select value = 'B'）{ do something}