How to pass a PHP variable to Javascript? [duplicate]

Answer 1

for another page you can use $_SESSION

<script type="text/javascript">
var timestamp = 0;
var currentroom = <?php echo $_SESSION['room']; ?>;
var heartbeatTimer;
var minHeartbeat = 3000;
var maxHeartbeat = 12000;
</script>

For same file/script sequence- its very simple, no need of SESSION

   var currentroom = <?php echo $room; ?>;

Answer 2

You can do this, when the JavaScript is generated by PHP. Example given:

<?php
...
$curmemid = intval($externalValue);
$strFind = 'SELECT * FROM cometchat_chatrooms_users WHERE userid='.$curmemid;
$result = mysql_query($strFind) or die(mysql_error());

if (isset($result)) {
    $row = mysql_fetch_array($result);
    $room = $row['chatroomid'];
} else
{
    echo 'There is something wrong!';
    $room = -1;
}
...
?>
<script type="text/javascript">
var timestamp = 0;
var currentroom = <?php echo $room; ?>;
var heartbeatTimer;
var minHeartbeat = 3000;
var maxHeartbeat = 12000;
</script>

Answer 3

<?php

$strFind="SELECT * FROM  cometchat_chatrooms_users WHERE userid=$curmemid";
$result=mysql_query($strFind) or die(mysql_error());
$row=mysql_fetch_array($result);
$room=$row['chatroomid'];

?>
<script type="text/javascript">
var timestamp = 0;
var currentroom = <?php if(isset($room))echo $room; else echo ""; ?>;
var heartbeatTimer;
var minHeartbeat = 3000;
var maxHeartbeat = 12000;
</script>

Answer 4

try to use Session to store your room variable and use it with javascript by the echo instruction

Answer 5

You cannot actually "pass" a variable anywhere. But only a scalar value. Frankly, you can pass only text data.
So, in case of javascript you have 2 options:

1. To generate whole js code from PHP along with all it's variables. Much like to how you generate HTML.

2. To request some variable from JS running in a browser, using AJAX technique.

Answer 6

The code will work as is. When the output (html and javascript) is generated by your php it will already have done the substitution. So your value will be inserted there as a literal. If it is a string, you'll still have to quote it though.

var currentroom = '$room';

will become

var currentroom = 'myroom';

in output.