Final solution
HTML code:
jQuery code:
$("a[data-toggle=modal]").click(function()
{
var essay_id = $(this).attr('id');
$.ajax({
cache: false,
type: 'POST',
url: 'backend.php',
data: 'EID='+essay_id,
success: function(data)
{
$('#myModal').show();
$('#modalContent').show().html(data);
}
});
});