A simple php js ajax interaction

simple-php-js-ajax-interaction

<?php
// the server script to go on to the PHP server

// header to allow CORS
header("Access-Control-Allow-Origin: *");

// declare the stub function to handle the GET request
function stub_function($val){
    // we can use the $val which is the GET parameter here
    echo "Hello!";
}

if(isset($_GET['value'])){
    // pass the get parameter to the stub_function
    stub_function($_GET['value']);
}
?>


// The client side JS code to call the above PHP script

var xhr = new XMLHttpRequest();
// server url with the GET parameter 
var server_url = 'http://myserver.com/server.php?value=test';
xhr.open('GET', server_url);
xhr.send(null);

// I assume a simple call_back function that prints the response code
function callback(response_code){
   console.log("The response is " + response_code);
}

xhr.onreadystatechange = function () {
  if (xhr.readyState === 4) {  
    // handle 200, 400 and 500 responses
    if (xhr.status === 200) 
      callback(xhr.responseText);
    } else if (xhr.status === 400){
      callback('Error: ' + xhr.status);
    } else if (xhr.status === 500){
      callback('Error: ' + xhr.status);
    } else {
      callback('Error: Other than 400 or 500 error. ' + xhr.status);
    }
  }
};