它不是在文本输入中显示数据

I have a drop down menu below and underneath that some text inputs. What I am trying to do is that when I select a course from the drop down menu, it should display the relevant details of the course selected in the text inputs. But nothing is being displayed in the text inputs. Now I am receiving no errors but I believe I am doing something incorrectly in my code for course details not being displayed in text inputs. How can I get the details displayed in the text inputs?

Below is mysqli code of drop down menu and retrieving Duration for each course:

$coursequery = "
SELECT CourseId, CourseNo, CourseName, Duration, CourseActive
FROM Course
WHERE
(CourseActive = ?)
ORDER BY CourseNo
";

... //mysqli prepare

$courseqrystmt->execute(); 

$courseqrystmt->bind_result($dbCourseId, $dbCourseNo, $dbCourseName, $dbCourseDuration, $dbCourseActive);

$courseqrystmt->store_result();

$coursenum = $courseqrystmt->num_rows();     

$courseHTML = '';

$courseHTML = '<select name="course" id="coursesDrop">'.PHP_EOL;
$courseHTML .= '<option value="">Please Select</option>'.PHP_EOL;           

$studentInfo = array();
$courseInfo = array();

while ( $courseqrystmt->fetch() ) {

$courseHTML .= sprintf("<option value='%s'>%s - %s</option>", $dbCourseId, $dbCourseNo, $dbCourseName) . PHP_EOL;   

$courseData = array();
$courseData["Duration"] = $dbCourseDuration;

array_push($courseInfo, $courseData);

}


$courseHTML .= '</select>';

Below is code for text inputs:

$editsession = "
<form id='updateForm'>

    <p><strong>Course Chosen:</strong></p>
    <table>
    <tr>
    <th></th>
    <td><input type='hidden' id='currentId' name='Idcurrent' readonly='readonly' value='' /> </td>
    </tr>
    <tr>
    <th>Course No:</th>
    <td><input type='text' id='currentCourseNo' name='CourseNocurrent' readonly='readonly' value='' /> </td>
    </tr>
    <tr>
    <th>Course Name:</th>
    <td><input type='text' id='currentCourseName' name='CourseNamecurrent' readonly='readonly' value='' /> </td>
    </tr>
    <tr>
    <th>Duration:</th>
    <td><input type='text' id='currentDuration' name='Durationcurrent' readonly='readonly' value='' /> </td>
    </tr>
    </table>
    </form>
";

echo $editsession;

Below is jquery code where it displays data in text inputs depending on course selected from course drop down menu:

 $(document).ready( function(){

                        var courseinfo = <?php echo json_encode($courseInfo);?>;

        $('#coursesDrop').change( function(){

            $('#targetdiv').hide();
            var courseId = $(this).val();


                        if (courseId !== '') {
        for (var i = 0, l = courseinfo.length; i < l; i++)
        {
                if (courseinfo[i].CourseId == courseId) { 

        var currentindex = $('#currentDuration').val(courseinfo[i].Duration);

                var text = $(this).find('option:selected').text();
                var split = text.split(' - ');
                $('#currentId').val($(this).find('option:selected').val());
                $('#currentCourseNo').val( split[0] );     
                $('#currentCourseName').val( split[1] );  

                break;
        }
       }

     }
                 else{
                $('#currentCourseNo,#currentCourseName,#currentDuration,#currentId,#studentselect').val('');         
        }

    });


        $('#courseForm').delegate('change','select',(function(warnings)
{
    return function()
    {
        warnings.html('');
    };
}($('#warnings'))));

});

Look at this jQuery function:

$.parseJSON();

When you define the var "courseinfo" the php is returning a string (in a json format). You need to transform this string in an object (or array) to easily access the content.

If your json_encode($courseInfo) returns proper json string.

you can simply use JSON.parse to turn the string into usable javascript object

var courseinfo = JSON.parse('<?php echo json_encode($courseInfo);?>');