错误无限滚动Javascript，向上滚动时不加载

Question

这个javascript有问题吗？我只想在滚动到达底部时加载数据，但现在如果向上滚动，数据就会加载，我不希望它是

var busy = false;
var limit = 6;
var offset = 0;
function displayRecords(lim, off) {
$.ajax({
type: "GET",
async: false,
url: "load/article-2.php",
data: "limit=" + lim + "&offset=" + off,
cache: false,
beforeSend: function() {
$("#loader_message").html("").hide();
$('#loader_image').show();
},
success: function(html) {
$("#results").append(html);
$('#loader_image').hide();
if (html == 0) {
$("#loader_message").html('<br><span class="margintop20 padding10">No more records.</span>').show()
} else {
$("#loader_message").html('<br><span class="margintop20"><img src="file-server/loading.gif" width="24" height="24"> Loading please wait...</span>').show();
}
window.busy = false;
}
});
}
$(document).ready(function() {
if (busy == false) {
busy = true;
displayRecords(limit, offset);
}
$(window).scroll(function() {
if ($(window).scrollTop() + $(window).height() > $("#results").height() && !busy) {
busy = true;
offset = limit + offset;
setTimeout(function() { displayRecords(limit, offset); }, 500);
}
});
});

这是我的php代码，如果你知道解决方案，请帮助我

PHP代码

$limit = (intval($_GET['limit']) != 0 ) ? $_GET['limit'] : 4; $offset = (intval($_GET['offset']) != 0 ) ? $_GET['offset'] : 0;
$article = "SELECT SQL_CALC_FOUND_ROWS * FROM article WHERE 1 AND status ='publish' ORDER BY id  DESC LIMIT $limit OFFSET $offset";
try {
$article1 = $pdo-> prepare($article); 
$article1 ->execute();
$results = $article1->fetchAll();
} catch (Exception $ex) {
echo $ex->getMessage();
}if (count($results) > 0) {
foreach ($results as $data) {
include("../data/data.php");
echo "
<div class='col-md-2 padding5 aos-item' data-aos='fade-up'>
<div class='col-md-12 bgputih shadow padding10 hover-dark'>
<a href='blog/$url' title='$stitle'> <img class='w-100 img-fluid' src='$fileserver/article/$dateimage/$imagem' alt='$stitle'> </a>
<hr>
<div class='titlearticle'>
<a href='blog/$url' title='$stitle'>$title</a>
</div>
<div class='font10'>
"; 
include("../includes/bawah/sumber.php");
include("../includes/bawah/article.php");
echo"
</div>
</div>
</div>
";
}
}

HTML代码

<div class='padding10 margintop-10 row' id="results"></div>
<div id="loader_image"><img src="<?php echo "$fileserver/loading.gif"; ?>" width="24" height="24"> Loading... please wait</div>
<div class="col-md-12" align="center" id="loader_message"></div>

结论：我只想在滚动到达底部时加载数据

Answer 1

只有当窗口滚动到底部时，才应该执行AJAX调用。

$(document).ready(function() {
//if (busy == false) { These lines will cause the AJAX call to be performed regardless of the window's scroll position and as such, they ought to be removed
//busy = true;
//displayRecords(limit, offset);
//}
$(window).scroll(function() {
if ((window.innerHeight + window.scrollY) >= document.body.offsetHeight && !busy) {
//you're at the bottom of the page
busy = true;
offset = limit + offset;
setTimeout(function() { displayRecords(limit, offset); }, 500);
}
});
});

JSFiddle：http://jsfiddle.net/jztnem4x/1/

Answer 2

在这里，您在检查$(window).scrollTop() + $(window).height() > $("#results").height() && !busy之前调用displayRecords一次

var busy = false;

if (busy == false) {
busy = true;
displayRecords(limit, offset);
}