I have an Infinite Scroll that loads more data (from DB) upon scrolling to the bottom,
However, when I try to include that file in another .PHP file and write any HTML tag at its top, it won’t load more posts.
On console, I get an error as
Uncaught SyntaxError: Unexpected token < in JSON at position 0
at JSON.parse (<anonymous>) at Object.success (test.php:126) at i (jquery-3.2.1.min.js:2) at Object.fireWith [as resolveWith] (jquery-3.2.1.min.js:2) at A (jquery-3.2.1.min.js:4) at XMLHttpRequest.<anonymous> (jquery-3.2.1.min.js:4)`
My code goes as :
getData.php
<?php
require_once('db.php');
if (! function_exists('getData')) {
/**
* @param int $offset
* @param int $limit
* @return array|null
*/
function getData($offset, $limit, $conn) {
$offset = (int)$offset;
$limit = (int)$limit;
$sqlQuery = "SELECT * FROM tbl_posts ORDER BY id DESC LIMIT $limit OFFSET $offset";
$result = mysqli_query($conn, $sqlQuery);
$rows = [];
while ($row = mysqli_fetch_assoc($result)) {
$cleanRow = [];
foreach ($row as $column => $value) {
$cleanRow[$column] = htmlentities($value);
}
$rows[]= $cleanRow;
}
return $rows;
}
}
Index.php
<?php
require_once ('getData.php');
$offset = (int)($_GET['offset'] ?? 0);
$dataOnly = (int)($_GET['dataOnly'] ?? 0);
$limit = 7;
$rows = getData($offset, $limit, $conn);
$offset+= $limit;
$data = [
'rows' => $rows,
'offset' => $offset,
];
$data = json_encode($data);
// if this is an ajax call, stop here and just spit out our json
if ($dataOnly) {
echo $data;
exit;
}
// otherwise, render the page
$sqlQuery = "SELECT * FROM tbl_posts";
$result = mysqli_query($conn, $sqlQuery);
$total_count = mysqli_num_rows($result);
?>
<script type="text/javascript" src="jquery-3.2.1.min.js"></script>
<style type="text/css">
body {
font-family: Arial;
background: #e9ebee;
font-size: 0.9em;
}
.post-wall {
background: #FFF;
border: #e0dfdf 1px solid;
padding: 20px;
border-radius: 5px;
margin: 0 auto;
width: 500px;
}
.post-item {
padding: 10px;
border: #f3f3f3 1px solid;
border-radius: 5px;
margin-bottom: 30px;
}
.post-title {
color: #4faae6;
}
.ajax-loader {
display: block;
text-align: center;
}
.ajax-loader img {
width: 50px;
vertical-align: middle;
}
</style>
<div class="post-wall">
<div id="post-list">
<input type="hidden" name="total_count" id="total_count" value="<?= $total_count ?>" />
<input type="hidden" name="offset" id="offset" value="<?= $offset ?>" />
</div>
<div class="ajax-loader text-center">
<img src="LoaderIcon.gif"> Loading more posts...
</div>
</div>
<script type="text/javascript">
$(document).ready(function(){
// load the initial rows on page load
let initialData = <?= $data ?? '' ?>;
if (initialData) {
if (initialData.rows) {
addrows(initialData.rows);
$('.ajax-loader').hide();
}
}
windowOnScroll();
});
function windowOnScroll() {
$(window).on("scroll", function(e) {
if ($(window).scrollTop() + 1 >= $(document).height() - $(window).height()) {
if ($(".post-item").length < $("#total_count").val()) {
let offset = $('#offset').val();
getMoreData(offset)
}
}
});
}
function getMoreData(offset) {
$('.ajax-loader').show();
$(window).off("scroll");
let pageUrl = window.location.href.split('?')[0];
$.ajax({
url: pageUrl + '?dataOnly=1&offset=' + offset,
type: "get",
success: function (response) {
response = JSON.parse(response);
if (response.rows) {
addrows(response.rows);
if (response.offset) {
$('#offset').val(response.offset);
}
$('.ajax-loader').hide();
}
windowOnScroll();
}
});
}
function addrows(rows) {
let postList = $("#post-list");
$.each(rows, function (i, row) {
let rowHtml = '<div class="post-item" id="'+row.id+'"><p class="post-title">'+row.title+'</p><p>'+row.content+'</p></div>';
postList.append(rowHtml);
});
}
</script>
Now please note that the above code works completely fine, as infinite scroll does exactly what it needs to be. But when I place it inside another file like
test.php
<div>
<?php include("index.php"); ?>
</div>
the first few posts (7) load and along with the loader.gif at the bottom. That’s all.
Any help is greatly appreciated.
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Answer
After basic understanding on what the error is trying to say, I finally figured out this as
ERROR:
Uncaught SyntaxError: Unexpected token < in JSON at position 0 at JSON.parse (<anonymous>) at Object.success (test.php:126) at i (jquery-3.2.1.min.js:2) at Object.fireWith [as resolveWith] (jquery-3.2.1.min.js:2) at A (jquery-3.2.1.min.js:4) at XMLHttpRequest.<anonymous> (jquery-3.2.1.min.js:4)
JSON should start with a valid JSON value – an object, array, string, number, or false/true/null. This response started with a < (hence the “Unexpected token <”).
That unexpected token, <, is a strong clue that the response was HTML instead of JSON.
The root cause is that the server returned HTML or some other non-JSON string.
So what I did was, just simply cut the JSON code into the top of the test.php leaving everything as it is.
index.php
<script type="text/javascript" src="jquery-3.2.1.min.js"></script>
<style type="text/css">
body {
font-family: Arial;
background: #e9ebee;
font-size: 0.9em;
}
.post-wall {
background: #FFF;
border: #e0dfdf 1px solid;
padding: 20px;
border-radius: 5px;
margin: 0 auto;
width: 500px;
}
.post-item {
padding: 10px;
border: #f3f3f3 1px solid;
border-radius: 5px;
margin-bottom: 30px;
}
.post-title {
color: #4faae6;
}
.ajax-loader {
display: block;
text-align: center;
}
.ajax-loader img {
width: 50px;
vertical-align: middle;
}
</style>
<div class="post-wall">
<div id="post-list">
<input type="hidden" name="total_count" id="total_count" value="<?= $total_count ?>" />
<input type="hidden" name="offset" id="offset" value="<?= $offset ?>" />
</div>
<div class="ajax-loader text-center">
<img src="LoaderIcon.gif"> Loading more posts...
</div>
</div>
<script type="text/javascript">
$(document).ready(function(){
// load the initial rows on page load
let initialData = <?= $data ?? '' ?>;
if (initialData) {
if (initialData.rows) {
addrows(initialData.rows);
$('.ajax-loader').hide();
}
}
windowOnScroll();
});
function windowOnScroll() {
$(window).on("scroll", function(e) {
if ($(window).scrollTop() + 1 >= $(document).height() - $(window).height()) {
if ($(".post-item").length < $("#total_count").val()) {
let offset = $('#offset').val();
getMoreData(offset)
}
}
});
}
function getMoreData(offset) {
$('.ajax-loader').show();
$(window).off("scroll");
let pageUrl = window.location.href.split('?')[0];
$.ajax({
url: pageUrl + '?dataOnly=1&offset=' + offset,
type: "get",
success: function (response) {
response = JSON.parse(response);
if (response.rows) {
addrows(response.rows);
if (response.offset) {
$('#offset').val(response.offset);
}
$('.ajax-loader').hide();
}
windowOnScroll();
}
});
}
function addrows(rows) {
let postList = $("#post-list");
$.each(rows, function (i, row) {
let rowHtml = '<div class="post-item" id="'+row.id+'"><p class="post-title">'+row.title+'</p><p>'+row.content+'</p></div>';
postList.append(rowHtml);
});
}
</script>
test.php
<?php
require_once ('getData.php');
$offset = (int)($_GET['offset'] ?? 0);
$dataOnly = (int)($_GET['dataOnly'] ?? 0);
$limit = 7;
$rows = getData($offset, $limit, $conn);
$offset+= $limit;
$data = [
'rows' => $rows,
'offset' => $offset,
];
$data = json_encode($data);
// if this is an ajax call, stop here and just spit out our json
if ($dataOnly) {
echo $data;
exit;
}
// otherwise, render the page
$sqlQuery = "SELECT * FROM tbl_posts";
$result = mysqli_query($conn, $sqlQuery);
$total_count = mysqli_num_rows($result);
?>
<div class="some">
<?PHP include("index.php"); ?>
</div>
And Voila. It works perfectly fine.
Thanks to @WesleySmith & @AngelDeykov for the time they spared on this.