try something like this :
$.ajax({
type: 'POST',
url: 'loginCheck',
data: $(formLogin).serialize(),
dataType: 'json',
success: function (textStatus, status) {
console.log(textStatus);
console.log(status);
},
error: function(xhr, textStatus, error) {
console.log(xhr.responseText);
console.log(xhr.statusText);
console.log(textStatus);
console.log(error);
}
});