Passing Javascript variable to PHP Page

[Vivz]

Here's my issue, I have this form name survey which have a textfield named: email on it

<form name="survey">
<label id="email">Email:</label><input id="email" type="text">
</form>

Email is store into a global variable in javascript.

<script>
var email = survey.email.value;
function openwindow() {
window.location.href = "test.php?email=" + email;
}
</script>

Now I have another button that suppoused to be executing function openwindow():

<input name="button" type="button" onClick="openwindow();" value="Send to PHP">

For some reason it is not happening, it stays in the same window and nothing change.

It needs to send the variable email to the PHP page so I can print it there:

The code for test.php is the following:

<?php
echo "<h1>Your Email is:</h1>";
echo "Email : ".$_GET['email']."<br>";
?>

[Vivz]

Just to let you guys know It now executes the test.php but the url is showing this:

/test.php?email=undefined <----why is not passing?

[Dr.Goodvibes]

Have you tried the following.

<script>
function openwindow() {
  var email = survey.email.value;
  window.location.href = "test.php?email=" + email;
}
</script>

[Vivz]

Yes I've tried that too, I declare the variable emaila s global so I can use it better inside any function.
Any other idea?