将“值”从表单中的选择传递到具有javascript问题的php变量

Question

I'm trying to pass a value of a option in a select from my HTML form to a PHP variable through Javascript

<script type="text/javascript">
function changeDir(ID){
    var dir = document.getElementById(ID).value;
    //For debuging purposes i've used an alert to show the value of dir on screen
    //alert (dir);
    //At this point of the function I want to assign the value of "dir" to the variable $folder
    }
</script>

there's my .php with html

<SELECT name="course" ID="course" onchange='changeDir("course")' >
        <OPTION value="artes>'">artes</OPTION>
        <OPTION value="ingles">inglés</OPTION>
</SELECT>
<?php $folder= ...?>

I'm using this with a php upload lib, all working at the same file. If anyone can explain me how to assign the value of the option to a php var will be great.

Thanks and Regards.

Answer 1

You can choose 2 different ways. First is AJAX, second is to redirect the page and GET the value of the <select> element.

HTML:

<SELECT name="course" ID="course" onchange='changeDir("course")' >
   <OPTION value="artes>'">artes</OPTION>
   <OPTION value="ingles">inglés</OPTION>
</SELECT>

JAVA:

<script type="text/javascript">
function changeDir(ID){
var dir = $("course").val();
$.post("php_file.php",
    {
      posted_dir: dir
    },
    function(data){
        $("id_of_result_elemnt").html(data);
    });
    }
</script

PHP:

<?php
$folder=$_POST['posted_dir'];
echo "This text will be display in the element with id_of_result_elemnt ID";
?>

Other method is redirect

HTML+PHP:

<SELECT name="course" ID="course" onchange='changeDir("course")' >
        <OPTION value="artes>'">artes</OPTION>
        <OPTION value="ingles">inglés</OPTION>
</SELECT>
<?php if (iset($_GET['folder']))
 {$_GET['folder']=$folder;}...?>

JAVA:

<script type="text/javascript">
function changeDir(ID){
    var dir = document.getElementById(ID).value;
    window.location = "http://example.com/myphp?folder=" + dir;
    }
</script>