js 1

dibawah ini javascript ajax, nah saya ingin mengubahnya menggunakan jquery, tp kenapa response http 415 terus ya:
function loadDoc() {
  var user = document.getElementById('name').value;
  var password = document.getElementById('password').value;
  var xhttp = new XMLHttpRequest();
  xhttp.onreadystatechange = function() {
    if (xhttp.readyState == 4 && xhttp.status == 200) {
      document.getElementById("demo").innerHTML = xhttp.responseText;
    }
  };
  xhttp.open("POST", "http://localhost:8080/SecurityApi/system/login", true);
  xhttp.send(btoa(user + ":" + password));
}

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var dats = btoa($("#name").val() + ":" + $("#password").val() );
    $.ajax({
      url:"http://localhost:8080/SecurityApi/system/login",
      type:"POST",
      data:btoa($("#name").val() + ":" + $("#password").val() ),
      contentType:"application/json; charset=utf-8",
      dataType:"json",
      success: function(msg){ alert(msg) }
    });