Trying to call PHP file using jQuery Ajax - php

Question

I am developing using jQuery 2.0.2 on Debian 7.0.0.
I am trying to call a PHP script from a JavaScript file using jQuery.ajax. My code is as follows.
jQuery.ajax({
type: "POST",
url: "DisplayParameters.php",
data: { LUT:lut,
Brightness: brightness,
Gamma: gamma,
Background: background}
}).done(function( result ) {
$("#msg").html( " Ajax called" );
});
At the beginning of DisplayParameters.php, I have the following.
?>
<script language="JavaScript">
alert('DisplayParameters');
</script>
<?php
but the alert box is not called. Firebug proceeds without any errors and shows the DisplayParameters.php text (with a +/- control to collapse and expand it). But the alert box is not called. I cannot get any feedback from DisplayParameters.php to trace what is happening.
What would be the best way for me to get feedback (like alert boxes or console.log) from DisplayParameters.php?

Answer 1

Your ajax call returns the contents of DisplayParameters.php as text, console.log(result) would show:
<script language="JavaScript">
alert('DisplayParameters');
</script>
If you want to add this extra code to the page (which I don't recommend unless you are sure you won't break the current page), you can try:
jQuery.ajax({
type: "POST",
url: "DisplayParameters.php",
data: { LUT:lut,
Brightness: brightness,
Gamma: gamma,
Background: background}
}).done(function( result ){
$("#msg").html( " Ajax called" );
$("body").append(result);
});
Another approach would be to serialize (JSON) the information you need, set the dataType: "json" option, and act based on this information.
If you will send HTML, ensure your PHP code doesn't shows any error or warning messages.

Answer 2

The alert() should happen inside .done() on the ajax call. Like the following:
.done(function(result) {
alert(result);
$("#msg").html( " Ajax called" );
});
And instead of alerting on DisplayParameters.php, use echo so that that will be the returned value for result. Like the following:
<script language="JavaScript">
//...some JS codes here
<?php echo 'DisplayParameters'; ?>
</script>