jquery - 多个选择的选定选项的长度始终返回 1

Question

有一个多重选择元素:

<select id="secta_code" name="secta_code[]" multiple="multiple" size="10"></select>

$(document).ready(function() {

    $('#secta_code').on('change',function() {
        alert("nb = "+$(this,"option:selected").length);
    });

});

如何动态捕获处理程序内选定选项的数量？

Answer 1

您可以使用以下替代方法:

    $('#secta_code').on('change', function () {
        alert("nb = " + $(":selected", this).length);
    });

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="secta_code" name="secta_code[]" multiple="multiple" size="10">
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
    <option value="5">5</option>
</select>

The jQuery constructor accepts a 2nd parameter called context which can be used to override the context of the selection.