刷新div内容而不关闭下拉列表

Question

I'm trying to learn php, mysql and javascript/jquery by building a live bidding system. I want to refresh the value of a bid button and dropdown automatically, but only if the value has changed. I've made a bidbuttons.php that outputs the buttons after querying the db for the current values, and I load and reload the page with this jquery I found elsewhere. I have tried several different methods of refreshing the div, and the best I came up with unfortunately closed the dropdown on the timer. This current version was described as exactly what I need but doesn't seem to work, in fact it logs me out. would prefer the div to refresh and the dropdown to close ONLY if the bidbuttons.php is updated. This is my first post, I hope I did this right.

<div id="bidbuttons"></div>

<script type="text/javascript">    
    var loadUrl = "includes/bidbuttons.php?id='.$item->id.'";  
    $("#bidbuttons").load(loadUrl).fadeIn("slow");
    var auto_refresh = setInterval(function () {
      $.get(loadUrl, function(data) {
        if (data.changed) {
          $("#bidbuttons").load(loadUrl).fadeIn("slow");
        }
      });
    }, 10000);
</script>

and my bidbuttons.php

    <?php
    include_once 'db_connect.php';
include_once 'functions.php';
sec_session_start();

if (login_check($mysqli) == true) { 
$getid = (int)$_GET['id'];

// get current price
    $result = $mysqli->query("SELECT ammount, bidder_id FROM bids WHERE ammount=(SELECT MAX(ammount)) && item_id like $getid order by ammount desc");
    while($row = $result->fetch_assoc()) {
        $bidder_id = $row["bidder_id"];
        $current = $row['ammount'];
        echo ($mysqli->error);
        $result->free();
    }
//get item info
    $results = $mysqli->query("SELECT * FROM items WHERE id like $getid ");
        while($row = $results->fetch_assoc()) {
            if (empty ($current)) { $current = $row["start"];}

            $title =  $row["title"];
            $item->thenext = ($current + $row["raise"]);
            $buyout = $row["buyout"];
            $raise =  $row["raise"];
            $sold = $row["sold"];

        }
        $results->free();


echo ('<div id="buttons">
    <a class="btn btn-primary btn-lg" style="margin-bottom: 10px; margin-top: 10px;  width: 80%;" href="includes\placebid.php?itemid=' . $getid . '&ammount=' . $item->thenext .'">Bid $' . $item->thenext . '</a>
    ');
if ($buyout){echo ('
<a class="btn btn-success btn-lg" style="margin-bottom: 10px; width: 80%;"  href="includes\placebid.php?itemid='.$getid.'&ammount='.$buyout.'">Buyout $'.$buyout.'</a>

');}
echo '</div><!-- buttons -->';
echo ('
    <div class="dropdown">
        <button style="margin-bottom: 10px; width: 80%;" type="button" class="btn btn-info btn-lg dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Custom Bid<span class="caret"></span></button>
<ul class="dropdown-menu">

');
// build the custom bid dropdown
    if (!$buyout) { $maxcust = $item->thenext*25;
        for ($cust = $item->thenext; $cust <= $maxcust; $cust = $cust + $raise) {
            echo ('<li><a href="includes\placebid.php?itemid=' . $id . '&ammount=' . $cust .'">' .$cust. '</a></li>');
        }
    }
    if ($buyout) {
        for ($cust = $item->thenext; $cust <= $buyout; $cust = $cust + $raise) {
        echo ('<li><a href="includes\placebid.php?itemid=' . $id . '&ammount=' .         $cust .'">' .$cust. '</a></li>');
        }   
}

echo ('
    </ul> 
    </div><!-- dropdown -->
'); 

}
mysqli_close($mysqli);
?>

Answer 1

I think the problem may be in that your PHP file is generating HTML which is continually replacing elements on your page due to them being loaded via AJAX.

Just an idea but you could make your PHP output a JSON instead that contains the database results, then have jQuery read the output. Your code would then process that JSON file and create or update the HTML elements accordingly (rather than replace them).

This way you have more fine grained control in the JavaScript for when your dropdown should close.

See this answer if you'd like to output from MySQLi to JSON.