<script type="text/javascript">
$(document).ready(function() {
    var course_data; // variable to hold data in once it is loaded
    $.get('courses.xml',function(data) { // get the courses.xml file
        course_data = data; // save the data for future use
                            // so we don't have to call the file again
        var that = $('#courses'); // that = the courses select
        $('course',course_data).each(function() { // find courses in data
            // dynamically create a new option element
            // make its text the value of the "title" attribute in the XML
            // and append it to the courses select
            $('<option>').text($(this).attr('title')).appendTo(that);
        });
    },'xml'); // specify what format the request will return - XML

    $('#courses').change(function() { // bind a trigger to when the
                                      // courses select changes
        var val = $(this).val(); // hold the select's new value
        var that = $('#times').empty(); // empty the select of times
                                        // and hold a reference in 'that'
        $('course',course_data).filter(function() { // get all courses...
            return val == $(this).attr('title'); // find the one chosen
        }).find('time').each(function() { // find all the times...
            // create a new option,set its text to the time,append to
            // the times select
            $('<option>').text($(this).text()).appendTo(that);  
        });
    });
});
</script>

Courses:
<select id='courses'>
    <option value='0'>----------</option>
</select>
<br>
Times:
<select id='times'>
    <option value='0'>----------</option>
</select>

它在做什么：

我正在使用$(document).ready();等待页面准备好.一旦它,我将加载文件courses.xml中的所有数据(您将更改为返回XML文件的任何数据).获得此数据后,我会填充课程< select>具有XML中所有课程的价值.然后我绑定一个触发器,每当课程< select>改变了.当发生这种情况时,我会找到所选择的课程并循环遍历时间< select>.

经过测试和工作.