AJAX Call Via Vanilla JavaScript In WordPress Plugin Development

I ama newbie in WordPress Plugin development in which I have some HTML form on the main plugin page that will get the data from the admin who is logged in and a back page where I have some different functions in PHP like to get information from the database etc. To explain in detail, here is the code…

Main Plugin File:

<?php /* Plugin Name: WP Testing Plugin Plugin URI: http://www.wordpress.org/WP-Testing-Plugin Description: A Detailed Description About This Plugin. Author: Muhammad Hassan Version: 0.1 Author URI: http://www.wordpress.org */  /*____________WP Testing Plugin Admin/Script_____________*/ function wp_testingPlugin_admin() {     echo '         <form id="searchForm" onsubmit="return searchData(this)">             <input name="WhatToSearch" type="text" />             <input type="submit" value="Search"/>             <input type="reset" value="Reset"/>             <div id="showReturnData"></div>         </form>     ';     echo '         <form id="infoForm" onsubmit="return searchInfo(this)">             <input name="WhatToKnow" type="text" />             <input type="submit" value="Search"/>             <input type="reset" value="Reset"/>             <div id="showReturnInfo"></div>         </form>     ';      echo '         <script type="text/javascript">             function searchData(incomingForm) {                 // Confirmation To Add A Data                 var answer = confirm("Are You Sure Want To Search?");                 if (answer){                     // If User Click Ok Then Execute The Below Code                          var FD = new FormData(incomingForm); // Get FORM Element Object                     FD.append("Function", "DataFunction"); // Adding Extra Data In FORM Element Object To Hit Only This Function In Ajax Call File                     var ajx = new XMLHttpRequest();                     ajx.onreadystatechange = function () {                         if (ajx.readyState == 4 && ajx.status == 200) {                             document.getElementById("showReturnData").innerHTML = ajx.responseText;                                      }                     };                     ajx.open("POST", "'.plugin_dir_url( __FILE__ ).'my_functions.php", true);                     ajx.send(FD);                     document.getElementById("showReturnData").innerHTML = "<div class="error">ERROR: AJAX Did Not Respond.</div>";                 }                 return false; // For Not To Reload Page             }               function searchInfo(incomingForm) {                 // Confirmation To Add A Data                 var answer = confirm("Are You Sure Want To Search?");                 if (answer){                     // If User Click Ok Then Execute The Below Code                          var FD = new FormData(incomingForm); // Get FORM Element Object                     FD.append("Function", "InfoFunction"); // Adding Extra Data In FORM Element Object To Hit Only This Function In Ajax Call File                     var ajx = new XMLHttpRequest();                     ajx.onreadystatechange = function () {                         if (ajx.readyState == 4 && ajx.status == 200) {                             document.getElementById("showReturnData").innerHTML = ajx.responseText;                                      }                     };                     ajx.open("POST", "'.plugin_dir_url( __FILE__ ).'my_functions.php", true);                     ajx.send(FD);                     document.getElementById("showReturnInfo").innerHTML = "<div class="error">ERROR: AJAX Did Not Respond.</div>";                 }                 return false; // For Not To Reload Page             }          </script>     '; //if you want only logged in users to access this function use this hook add_action('wp_ajax_searchData', 'searchData'); add_action('wp_ajax_searchInfo', 'searchInfo'); //if you want none logged in users to access this function use this hook add_action('wp_ajax_nopriv_searchData', 'searchData'); add_action('wp_ajax_nopriv_searchInfo', 'searchInfo');   } /*__________________________________________________________________*/   /*____________WP Testing Plugin Option_____________*/ //Adding "WP Testing Plugin" Menu To WordPress -> Tools function wp_testingPlugin() {     //  add_management_page( $  page_title, $  menu_title, $  capability, $  menu_slug, $  function);                  Menu Under Tools     add_management_page("WP Testing Plugin By Hassan", "WP Testing Plugin", 'activate_plugins', "WP-Testing-Plugin", "wp_testingPlugin_admin"); } add_action('admin_menu', 'wp_testingPlugin'); /*__________________________________________________________________*/ ?> 

And this is my_functions.php file.

<?php /****************************************************************************/ //Garb The Function Parameter /****************************************************************************/ $  Function = $  _POST['Function'];   /****************************************************************************/ // Run Search Function /****************************************************************************/ if ($  Function == "DataFunction"){      if(!isset($  _POST['WhatToSearch'])){         $  WhatToSearch = "Nothing";     } else {         $  WhatToSearch = $  _POST['WhatToSearch'];     }      echo "<div class='success'>SUCCESS: Function Is Working Perfectly And Getting Data ".$  WhatToSearch.".</div>"; }  /****************************************************************************/ // Run Another Function /****************************************************************************/ if ($  Function == "InfoFunction"){      if(!isset($  _POST['WhatToKnow'])){         $  WhatToKnow = "Nothing";     } else {         $  WhatToKnow = $  _POST['WhatToKnow'];     }      echo "<div class='success'>SUCCESS: Function Is Working Perfectly And Getting Data ".$  WhatToKnow.".</div>"; }  ?> 

But my code is not working and not hitting my_functions.php file even. Whats the problem here? Need basic step only to work in this patteren. Currently, I am not sure I am even implementing this correctly as I never used WP AJAX before. So right now, my objective is just to get a basic example working. I appreciate any suggestions on how to accomplish this.

Thank you!