jQuery send data to a new open tab and get the data

I want to send some data from ClassA to ClassB . So what I did is I create a hidden form in my ClassA view page and post it to ClassB.

<form id="invisible_form" action="classB" method="post" target="_blank">
    <input id="post_to_chatroom" name="hiddenform" type="hidden" value="default">
</form>

Then from the js part

let recid   = $(this).attr('data-recid');
let chatid  = $(this).attr('data-chatid');
$('#post_to_chatroom').attr({
    'post_recid' : recid,
    'post_chatid': chatid
});
$('#invisible_form').submit();

But then I dont know how can I get the post data from ClassA. I have tried getting the data from $_POST in the php controller but it didnt work.

ClassB controller

$t1 = isset($_POST['post_recid']) ? $_POST['post_recid'] : 'null';
$t2 = isset($_POST['post_chatid']) ? $_POST['post_chatid'] : 'null';
$jscript = "var postRecid =".$t1.";";
$jscript .= "var postChatid =".$t2.";";

but what I get is all null value. So how can I get the post data value from class A?

Answer

With post data you can only send value attribute. You can add another two hidden fields.

<input name="post_recid" type="hidden" value="Your value">
<input name="post_chatid" type="hidden" value="Your value">

Or you can use jquery post to send data without submission.