如何通过onchange函数将带有选项值的输入类型的PHP值传递给Javascript？

Question

I have a table of employees and I need to show the salary of every employee of the selected month, so I need to pass two values into the function that is called on the onchange , the value of the month with the employee id so to calculate the salary of the particular employee.

Salary section:

JavaScript:

<script>

function calSal(month,hidVal)
{
    var mon = month.value;
    alert(mon);
    var hidVal = hidVal.value;
    alert(hidVal);
}

</script>

PHP:

<?php
    $query=mysqli_query($con,"select employee_first_name , employee_code ,e_id from add_employee");
    $a=0;
    while($result=mysqli_fetch_array($query))
    {
        $e_id[] = $result['e_id'];
        $employee_first_name = $result['employee_first_name'];
        $employee_code = $result['employee_code'];
?>                          
         <tr>
             <td align="center"><?php print_r ($e_id[$a]); ?><input type="hidden" value="<?php echo $e_id; ?>" id="id<?php echo $a; ?>"/></td>
             <td align="center"><?php echo $employee_first_name. ' : ' .$employee_code; ?></td>
             <td align="center">
                 <input type="text" value="<?php echo $a; ?>" id="hidVal<?php echo $a; ?>"/>
                      <select class="form-control select1" onchange="calSal(this, 'hidVal' );">
                          <option value="01">January</option>
                          <option value="02">Feburary</option>
                          <option value="03">March</option>
                          <option value="04">April</option>
                          <option value="05">May</option>
                          <option value="06">June</option>
                          <option value="07">July</option>
                          <option value="08">August</option>
                          <option value="09">September</option>
                          <option value="10">October</option>
                          <option value="11">November</option>
                          <option value="12">December</option>
                      </select>
                 </td>
                 <td align="center"></td>
             </tr>
         <?php
         $a++;   
     }
?>

Answer 1

You are passing only 'hidVal' as text with onchange="calSal(this, 'hidVal' );" You have to pass $('#hidVal<?php echo $a; ?>') there. So that you can grab value with hidVal.value in javascript function.