javascript - 从先前的选择框值填充选择框选项

Question

我在填充选择框选项时遇到问题，具体取决于先前的选择框

问题是每当我从第一个选择框中选择值(即#city)时，它都会给我城市值的结果，这很好，但是一旦我选择第二个值，它就会给我第二个值的结果以及第一个值。

下面是我的代码

HTML 代码

<lable>City</lable>
<select id="city" style="width:100%;text-align:left;" onchange="getSchool()"></select>
<span id='paymentform_city_errorloc' class='error'></span>
<br>
<br>
<lable>School</lable>
<select id="school" style="width:100%;">

</select>
<span id='paymentform_school_errorloc' class='error'></span>
<br>
<br>

JS 代码

 var cityname, city, schoolname, schooldata, cityid, city1;
            var cityarray = [];
            var schoolarray = [];

            function getCity() {
                jQuery.ajax({
                    url: baseurl + "getcity.php",

                    async: true
                    , success: function (data) {
                        data = $.trim(data);
                        if (data == "false") {
                            console.log(data);

                        } else {

                            var myArray = jQuery.parseJSON(data);

                            jQuery(myArray).each(function (index, element) {
                                cityname = element.cityname;
                                cityid = element.city_id;
                                cityarray.push([cityname, cityid])
                            });
                            for (var i = 0; i < cityarray.length; i++) {
                                city1 += '<option value="' + cityarray[i][1] + '">' + cityarray[i][0] + '</option>';

                            }

                            $('#city').html("<option disabled selected></option>" + city1);
                        }
                    }

                });
            }

  function getSchool() {
            var city_id = $('#city').val();
            jQuery.ajax({
                url: baseurl + "getschool.php"
                , data: 'cityid=' + city_id
                , type: "POST"
                , success: function (response) {
                    response = $.trim(response);
                    if (response == "false") {

                               $('#school').prop('disabled', 'disabled');

                    } else {
                        $('#school').prop('disabled', false);
                        console.log(response);
                        $('#school').append(response);


                    }

                }
                , error: function () {}
            });
        }

Answer 1

 function getSchool() {
            var city_id = $('#city').val();
            schoolarray = []; //Add this code.

进行上述更改。每次选择新城市时，您的学校阵列都会重置。