jquery- ajax发布到php一个空变量[重复]

View:

<table>
<tr>
<td id="percentage">Percentage:&nbsp; <?php echo $percentage; ?> %</td>
</tr>
</table>

 <div class="box-footer" style="float: right">
        <a href="<?php echo base_url(); ?>student/Examinations" class="btn btn-primary" style="font-size: 20px;" id="submit">Submit</a>
    </div>

<script>
    $(document).ready(function () {
        var percentage = $("#percentage").text();
        console.log(percentage);                //Percentage:  28.57 %
        $("#submit").click(function () {
            $.ajax({
                type: 'POST',
                url: base_url + "student/Examinations",
                data: {percentage: percentage},
                success: function () {

                }
            });
        });
    });
</script>

Controller:

class Examinations extends CI_Controller {
 function __construct() {
        parent::__construct();
}
 public function index() {
        $percentage = $_POST["percentage"];
        var_dump($percentage);           // var_dump null
}
}

MY Question: javascript variable(percentage) to pass controller , and var_dump is null why?please help me.....................................

</div>

Not a user of code igniter myself, but using other frameworks, you better use the request object.

I quickly perused code igniter documentation, and apparently you should do something like that :

$percentage = $this->input->post('percentage');

It behaves like that because You are doing 2 things here. It looks like that:

• You click on link with id="submit"
• $(#submit).click() is executed:
  • ajax call with parameter percentage is executed
  • ajax call with no handled response ends (empty function in success, so You don't even see result of Your click event)
• Web browser continues to act normally - it follows clicked link and goes to url: "<?php echo base_url(); ?>student/Examinations" with no percentage parameter

If You want to send param just modify Your href like that: "<?php echo base_url(); ?>student/Examinations?percentage=sample_value" and check in target script $_GET['percentage']

you have not prevented execution of anchor tag, you have to prvent event of a tag

$(document).ready(function () {
    $("#submit").click(function (e) {
       e.preventDefault();
        $.ajax({
            type: 'POST',
            url: base_url + "student/Examinations", // or you can take $("#submit").attr('href');
            data: {percentage: $("#percentage").text()},
            success: function(data) {
                console.log(data);
            }
        });
        return false;
    });
});