How to send and recieve info from php file with XMLHttpRequest?
I try using XMLHttpRequest and jquery ajax. In both cases work find, but I can't extract the data.
Js file
var parametros = {
            "url" : url
    };
  var xhr = new XMLHttpRequest();
  xhr.open("POST", "file.php", true);
  xhr.onreadystatechange = function() {
  if (xhr.readyState == 4) {
    alert(xhr.responseText)
  }
}
xhr.send(parametros);
file.php
  <?php 
$str = $POST['url'];
echo $str;
    ?>
The alert show me all the php file, with php tags (plain text). How to recieve only the $str var?
EDIT: manifest file:
{
  "name": "Get pages source",
  "version": "1.0",
  "manifest_version": 2,
  "description": "Get pages source from a popup",
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "permissions": ["http://localhost/extencio/*"]
}
 
     
    