JavaScript cannot actively read variables from the server, but when a page loads, PHP can pass variables to JavaScript by writing to the page the JavaScript is on.
Code:
<?php
$username = "Snib";
?>
...
<script language="javascript" type="text/javascript">
var sStr = "My name is <?php echo $username ?>.";
document.write(sStr);
</script>
...
This code will output this text:
Code:
...
My name is Snib.
...
By editing the JavaScript on the page, PHP can set JavaScript variables.
This is very useful for passing database values to JavaScript to compare with a JavaScript variable or number. Let's say that there is a MySQL database called db1, with a table called table1, which has two columns, 'userid' and 'usernum'. To retrieve information about Snib, you can use code like this:
Code:
<?php
$connection = mysql_connect('localhost', 'username', 'password');
$sql = mysql_select_db('db1', $connection);
$userid = "Snib";
$query = "SELECT * FROM `table1` WHERE userid='$userid'";
$result = mysql_query($query);
$data = mysql_fetch_assoc($result);
$usernum = $data['usernum'];
?>
<script language="javascript" type="text/javascript">
var userid = "<?php echo $userid; ?>";
var usernum = "<?php echo $usernum; ?>";
//if usernum is less than or equal to 50
if (usernum <= 50) {
alert("You are not allowed on this page, " + userid);
setTimeout('window.location = "otherpage.php"', 3000); // user leaves in 3 seconds
} else {
alert('Welcome to this page, ' + userid);
}
</script>
<?php mysql_close($connection); ?>
Although setting JavaScript variables with PHP is helpful, it cannot always be done. For instance, PHP cannot modify external .
js documents temporarily. It changes them for good.
Reference:
MySQL with PHP:
http://php.net/mysql
JavaScript
:
http://javascript.com http://msdn.microsoft.com/library/default.asp (JScript and DHTML)
Snib
P2P Member
<><
Q. How do I pass PHP variables to JavaScript?
