javascript error: variable is not defined

Question

to is not defined
[Break on this error] setTimeout('updateChat(from, to)', 1);

I'm getting this error... I'm using Firebug to test and this comes up in the Console. The error corresponds to line 71 of chat.js and the whole function that wraps this line is:

function updateChat(from, to) {

    $.ajax({
        type: "POST",
        url: "process.php",
        data: {
            'function': 'getFromDB',
            'from': from,
            'to': to
        },
        dataType: "json",
        cache: false,
        success: function(data) {

            if (data.text != null) {
                for (var i = 0; i < data.text.length; i++) {  
                    $('#chat-box').append($("<p>"+ data.text[i] +"</p>"));
                }
                document.getElementById('chat-box').scrollTop = document.getElementById('chat-box').scrollHeight;
            }
            instanse = false;
            state = data.state;
            setTimeout('updateChat(from, to)', 1); // gives error
        },  
    });
}

This links to process.php with function call getFromDB and the code for that is:

case ('getFromDB'):

    // get the sender and receiver user IDs from their user names
    $from = mysql_real_escape_string($_POST['from']);
    $query  = "SELECT `user_id` FROM `Users` WHERE `user_name` = '$from' LIMIT 1";
    $result = mysql_query($query) or die(mysql_error());
    $row = mysql_fetch_assoc($result);
    $fromID = $row['user_id'];  

    $to = mysql_real_escape_string($_POST['to']);
    $query  = "SELECT `user_id` FROM `Users` WHERE `user_name` = '$to' LIMIT 1";
    $result = mysql_query($query) or die(mysql_error());
    $row = mysql_fetch_assoc($result);
    $toID = $row['user_id'];

    $query = "SELECT * FROM `Messages` WHERE `from_id` = '$fromID' AND `to_id` = '$toID' LIMIT 1";
    $result = mysql_query($query);
    while($row = mysql_fetch_assoc($result)) {

        $text[] = $line = $row['message'];
        $log['text'] = $text;

    }

    break;

So I'm confused with the line that is giving the error. setTimeout('updateChat(from,to)',1); aren't the parameters to updateChat the same parameters that came into the function? Or are they being pulled in from somewhere else and I have to define to and from else where? Any ideas how to fix this error?

Thanks, Hristo

Pekka · Accepted Answer · 2010-06-17 18:40:50Z

7

This could be because when defining the setTimeout function this way, the current function's scope doesn't apply. I don't know exactly to be honest. Should be easy to find out, though: Try

 setTimeout(function() { updateChat(from, to) }, 1);

If it works, that's it.

if that's not it: Are you sure to gets passed to your first updateChat() call in the first place?

answered Jun 17, 2010 at 18:40

Pekka

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10 Comments

Bob Fincheimer Over a year ago

javascript closures = win... you beat me by a minute :-(

Hristo Over a year ago

Yes... both 'to' and 'from' both get passed into the function correctly. This seemed to get rid of the error however it caused an infinite loop and the message I post keeps getting posted infinitely.

Pekka Over a year ago

@Hristo I think that's because your function is not specifying a condition when not to add the setTimeout()?

Hristo Over a year ago

Could it be that I'm POST-ing and then calling the same function which would create the loop?

Pekka Over a year ago

@Hristo yes. What you have right now is designed to work as an infinite loop.

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