How can I reload a page and display a query parameter with PHP + JS?

Question

function myfun()
{
  var nm=12;
  window.location.href="bkd.php?uid="+nm;
}

<form name="frm" method="GET">
  <input type="text" value="ghf" onclick="myfun();"></input>
  <input type="hidden" value="" name="txtval" id="txtval"></input>
  <?php 
    echo $_GET["uid"];
  ?>
</form>

I have added JS and HTML on the same page. Wwhen I execute the code I am getting the value in PHP but it also displays

"Undefined index: uid"

Js is client side script, while php is the server side script. The php script is executed on the server side, where js code has not been executed. — LF-DevJourney
– LF-DevJourney, Commented Nov 14, 2017 at 9:40
I believe the title is unclear. I think OP wants to reload the page with JS populating the uid query parameter and use PHP to display it on reload. — Jim Wright
– Jim Wright, Commented Nov 14, 2017 at 9:43
if (isset($_GET["uid"])) echo $_GET["uid"];. This will check for the existence of the variable before it displays it. It won't exist until you reload the page via your JS function. Therefore this code will stop it trying to display the value when you have first loaded the page manually. — ADyson
– ADyson, Commented Nov 14, 2017 at 10:31

Jim Wright · Accepted Answer · 2017-11-14 09:46:01Z

3

The first time you load the page $_GET['uid'] might not be set so you need to check it. You can use array_key_exists() for this.

I would also recommend putting the onclick action on a button rather than the text field.

function myfun()
{
    var nm=12;
    window.location.href="bkd.php?uid="+nm;
}

<form name="frm" method="GET">
<input type="text" value="ghf"></input>
<input type="hidden" value="" name="txtval" id="txtval"></input>
<input type="button" onclick="myfun();"></input>
<?php
if (array_key_exists("uid", $_GET)) { 
    echo $_GET["uid"];
}

?>
</form>

edited Nov 14, 2017 at 9:46

answered Nov 14, 2017 at 9:36

Jim Wright

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