Php variable not getting incremented in jquery - php

Question

I want to increment $j in $.each function of jquery. But $j is not getting incremented. What may be the reason. My code is as follows:
$.ajax
({
url : "test.php",
type : "post",
data : {
"categoryIds" : categoryIds
},
dataType : "json",
success : function(resp){
var html = "";
var i = 1;
<?php $j = 1; ?>
$.each(resp,function(key,questions ){
<?php
$j = 1;
$testdataIndex = "answer_".$j;
?>
var test = "<?php echo $testdataIndex?>";
alert(test);
var res = "<?php echo $_SESSION['testdata'][$testdataIndex]; ?> ";
var index = "<?php echo $j++;?>";
alert(index);
});
});
Each time test prints 'answer_1' and index as 1

Answer 1

Fixed session issue :
$.ajax
({
url : "test.php",
type : "post",
data : {
"categoryIds" : categoryIds
},
dataType : "json",
success : function(resp){
var html = "";
var i = 1;
<?php $j = 1; ?>
$.each(resp,function(key,questions ){
var testdataIndex = "answer_" + i ;
var filename = "getsession.php?sessionName="+testdataIndex;
$.get(filename, function (data)
{
sessionValues = data;
$("#"+testdataIndex).text(sessionValues);
});//get
html += '<textarea class="form-control answer" rows = "5" style="width:127%;" id="answer_'+i+'" name="answer_'+i+'" required="required"></textarea>';
i++;
});//each
});//ajax
getsession.php
<?php
session_start();
$sessionName = $_GET['sessionName'];
print ($_SESSION['testdata'][$sessionName]);
?>
I have answered my question for other who face same problem.