Store in php variable onclick()

[BIOSTALL]

Hey, i have a textbox and an image.... When the image is clicked, i need all the text in the textbox to be stored in a PHP session variable.

Is this possible?

i was going to do womething like this:

<script>
function assignvariable() {
var currentvalue = document.form1.message.value;
document.write("<?php $_SESSION['message'] = " + currentvalue);
}
</script>

Would someone mind telling me if this is the way to go about it??

Many thanks, BIOSTALL