Ajax自动刷新评论墙

Alright, so after several days of searching and reading I still can't get this to work so this is kinda my last chance. Keep in mind i'm a rookie with Ajax and JS.

I have a comment wall where you can leave a nice little message to others on the page and it works just fine but now I want to add some ajax so it auto refresh every 10 second and get the latest comments.

The thing is I get the whole website to be displayed inside that div and not the comments.

I have a js document with the following code

  (function update() {
    $.ajax({
        type : 'GET',
        url : 'index.php',
        success : function(data){
            $('#cmt_wall_container').html(data);
        },
    }).then(function() {
       setTimeout(update, 10000);
    });
})(); 

And my Index.php page include the following

<?php include_once 'connect.php'; ?>
<?php 
$cmt_list = "";
$sql = mysqli_query($con, "SELECT * FROM cmt ORDER BY id DESC LIMIT 10");
$cmtCount = mysqli_num_rows($sql);
if($cmtCount > 0){
    while($row = mysqli_fetch_array($sql)){
       $id = $row["id"];
       $comment = $row["comment"];
       $cmt_list .="<div class='post-container'><p class='post-comment'>$comment</p></div>";
}
} else {
    $cmt_list = "leave a comment";
}
?>

<head>stuff..</head>
<body>
    <div id="cmt_wall_container">
        <?php echo $cmt_list; ?>
    </div>
</body>

I hope this is clear enough! Thank you very much in advance, you are really my last hope!!!!!

Try something more along these lines...

THE JS SCRIPT:

function update() {
    $.post( "index.php", { grab: "comments"}).done(function( data ) {
        $('#cmt_wall_container').html(data);
        setTimeout(update, 10000);
    });
}

THE PHP SCRIPT:

<?php 
    include_once 'connect.php'; 

    $cmt_list = "";
    $sql = mysqli_query($con, "SELECT * FROM cmt ORDER BY id DESC LIMIT 10");
    $cmtCount = mysqli_num_rows($sql);
    if($cmtCount > 0){
        while($row = mysqli_fetch_array($sql)){
           $id = $row["id"];
           $comment = $row["comment"];
           $cmt_list .="<div class='post-container'><p class='post-comment'>$comment</p></div>";
    }
    } else {
        $cmt_list = "leave a comment";
    }
    // Return Results To Ajax And Exit
    if (isset($_POST['grab']) && $_POST['grab']==="comments") {
        echo $cmt_list;
        exit;
    } // Else Load Page As Normal
?>
<head>stuff..</head>
<body>
    <div id="cmt_wall_container">
        <?php echo $cmt_list; ?>
    </div>
</body>

By using isset, you can detect if your requesting from ajax and only return the comments else you load the reset of the page as normal.. Its one method / approach.

Note this still applies for $_GET.. just change $_POST to $_GET if you need, but by using the exit option.. You dont need to wrap your whole site in a else statement.. its cleaner

So change your ajax url to index.php?grab=comments and add this below your PHP code.

    if (isset($_GET['grab']) && $_GET['grab']==="comments") {
        echo $cmt_list;
        exit;
    } 

By using this approach, you can also control your comments with options like grab=admin_comments or how ever you would want.

It should work as 8BitProgrammer suggested

(function update() {
  $.ajax({
    type : 'GET',
    url : 'index.php?comments=true',
    success : function(data){
      $('#cmt_wall_container').html(data);
    },
  }).then(function() {
    setTimeout(update, 10000);
  });
})(); 

php:

<?php include_once 'connect.php'; ?>
<?php 
$cmt_list = "";
$sql = mysqli_query($con, "SELECT * FROM cmt ORDER BY id DESC LIMIT 10");
$cmtCount = mysqli_num_rows($sql);
if($cmtCount > 0){
    while($row = mysqli_fetch_array($sql)){
       $id = $row["id"];
       $comment = $row["comment"];
       $cmt_list .="<div class='post-container'><p class='post-      comment'>$comment</p></div>";
}
} else {
$cmt_list = "leave a comment";
}

if ($_GET["comments"]):
?>
    <?php echo $cmt_list; ?>
<?php
else :
?>
    <head>stuff..</head>
    <body>
        <div id="cmt_wall_container">
            <?php echo $cmt_list; ?>
        </div>
    </body>
<?php
endif;
?>