Réception PHP d'un POST JSON Ajax

<?php
  $result = array();

//recuperation propre des variables
 $user = !empty($_POST['user']) ? $_POST['user'] : NULL;
 $pass= !empty($_POST['pass']) ? $_POST['pass'] : NULL;
 
//traitement
 if($user && $pass){
  
   $result = array("result"=>"ok","user"=>$user,"pass"=>$pass);
 
 }else{
      $result = array("result"=>"KO","post"=>$_POST);
 }

//renvoi du resultat au format json
echo json_encode($result);
?>

var result = {
user: usernameResult,
pass: passwordResult
}
$.ajax({
    type: "POST",
    url: 'views/connexion.php',
    data: result,
    success: window.location.href = 'views/connexion.php',
    dataType: 'json'
});
window.location('views/connexion.php');

var datas = {user: usernameResult,pass: passwordResult};

$.ajax({
    type: "POST",
    url: 'views/connexion.php',
    data: datas,
    dataType: 'json',
    success: function(reponse){
       console.log(reponse);
       //window.location('views/connexion.php'); //le temps des tests on désactive cette redirection
    },
    error:function(jqXHR, textStatus){
      console.log('error :' + textStatus + ' : ' + jqXHR.responseText);
      alert('Erreur ' + jqXHR.responseText );
    }
   
});