使用jquery更新php值

Question

<?php
$date="2016-01-01"; 
?>
<script type="javascript">
       $(document).ready(function(){
              $('#prev').click(function(){
              var myVar2=<?php echo json_encode($date);?>;
              alert(myVar2);
              var myVar=<?php $date2=date('Y-m-d',strtotime('-1 day',strtotime($date))); $date=$date2; echo json_encode($date); ?>;
              alert(myVar);
              myVar2=<?php echo json_encode($date);?>;
              alert(myVar2);
              }
       })
</script>
<input type="button" value="prev" id="prev" />

I need to decrement the value of the variable date every time the button with id="prev" is clicked. The problem here is that the value of the variable date is not getting updated

Answer 1

If you are using sessions, you will need an ajax call that will call a php file within the session that will update a particular session variable. The issue at hand though is that it would not be an update until the next time the base page was loaded since that information would need to be accessed.

In your sample, you will need the page to say:

session_start();

and then something like:

$date = isset($_SESSION["date"]) ? $_SESSION["date"] : "2016-01-01";

and then on the front end you will need to do an ajax post request to the a file with the data key being "date":

session_start();
$_SESSION["date"] = $_POST["date"];

then each time you load the page, as long as session is maintained it will keep up with a date, with the default value being: "2016-01-01"