jQuery/JSON/PHP failing - php

Question

I am trying to call a php script that accepts JSON data, writes it into a file and returns simple text response using jQuery/AJAX call.
jQuery code :
$("input.callphp").click(function() {
var url_file = myurl;
$.ajax({type : "POST",
url : url_file,
data : {puzzle: 'Reset!'},
success : function(data){
alert("Success");
alert(data);
},
error : function (jqXHR, textStatus, errorThrown) {
alert("Error: " + textStatus + "<" + errorThrown + ">");
},
dataType : 'text'
});
});
PHP Code :
<?php
$thefile = "new.json"; /* Our filename as defined earlier */
$towrite = $_POST["puzzle"]; /* What we'll write to the file */
$openedfile = fopen($thefile, "w");
fwrite($openedfile, $towrite);
fclose($openedfile);
echo "<br> <br>".$towrite;
?>
However, the call is never a success and always gives an error with an alert "Error : [Object object]".
NOTE
This code works fine. I was trying to perform a cross domain query - I uploaded the files to the same server and it worked.

Answer 1

var url_file = myurl"; // remove `"` from end
Arguments of error function is:
.error( jqXHR, textStatus, errorThrown )
not data,
You can get data (ie. response data from server) as success() function argument.
Like:
success: function(data) {
}
For more info look .ajax()
NOTE
If you're trying to get data from cross-domain (i.e from different domain), then you need jsonp request.

Answer 2

Your data object isn't valid; the key shouldn't be quoted:
data : { puzzle: 'Reset!' }
In addition, SO's syntax highlighting points out that you have missed out a " in your code:
var url_file = myurl";
Should be
var url_file = "myurl;