当选择了另一个“选择”下拉列表中的一个选项时，如何显示“选择”下拉列表

Question

我想在选择另一个select元素的一个选项时显示一个select元素，在选择另一个选项时隐藏它。

   Country:
<select name="country" class="country">
    <option value="Canada">Canada</option>
    <option value="United_States">United States</option>
</select>
<br>Province/State:
<select name="pro" class="pro">
    <option value="BC">British Columbia</option>
    <option value="Ontario">Ontario</option>
</select>

这是JavaScript：

$('.country').on('change', function (e) {

    var optionSelected = $("option:selected", this);
    var valueSelected = this.value;
if(valueSelected == "Canada") {
$('.pro').html('<option value ="BC">British Columbia</option><option value="Ontario">Ontario</option>');
    // remove the city <select> dropdown
               } else if (valueSelected == "United_States") {
$('.pro ').html('<option value ="FL">Florida</option><option value="NY">New York</option>');
}
});
$('.pro').on('change', function (e) {
    var optionSelectedb = $("option:selected", this);
    var valueSelectedb = this.value;
    if(valueSelectedb == "Florida") {
    // write <select name="city" class="city"><option value="Miami">Miami</option><option value="Orlando">Orlando</option> </select>
    } else if(valueSelectedb == "New York") {
//    write <select name="city" class="city"><option value="New York">New York</option><option value="Buffalo">Buffalo</option></select>
    }   
});

感谢任何帮助。谢谢

Answer 1

https://jsfidle.net/jascd6ue/1/

$('.country').on('change', function (e) {

    var optionSelected = $("option:selected", this);
    var valueSelected = this.value;
    if (valueSelected == "Canada") {
        $('.pro').html('<option value ="BC">British Columbia</option><option value="Ontario">Ontario</option>');
        // remove the city <select> dropdown
    } else if (valueSelected == "United_States") {
        $('.pro ').html('<option value ="FL">Florida</option><option value="NY">New York</option>');
    }
});
$('.pro').on('change', function (e) {
    var optionSelectedb = $("option:selected", this);
    var valueSelectedb = this.value;
    console.log(valueSelectedb);
    $(".city option").remove();
    if (valueSelectedb == "FL") {
        $(".city").append("<option value=\"Miami\">Miami</option><option value=\"Orlando\">Orlando</option>");
    } else if (valueSelectedb == "NY") {
        $(".city").append("<option value=\"New York\">New York</option><option value=\"Buffalo\">Buffalo</option></select>");
    }
});

但我会修改一些代码。您可以编写包含所有州和城市的数组，然后使用循环生成选项